Document:

EX-10.7

 Exhibit 10.7 

DATED 
  

 
 RULES OF 

THE MIMECAST LIMITED 2010 EMI SHARE OPTION SCHEME 

(approved by the Board on 23 March 2010) 

(amended by the Board on 28 April 2015) 
  

 
  
 

 
 Berlin, Brussels, Cambridge, Dubai, Düsseldorf, Frankfurt, Hamburg, London, Munich, Paris. 

Representative offices: Alicante, Beijing, Shanghai. Associated office: Warsaw 

 Index 
  

							
	Clause No.	  	Page No.	 
			
	1.	 	Interpretation and Construction	  	 	3	  
			
	2.	 	Statement of Purpose	  	 	7	  
			
	3.	 	Grant of Options	  	 	7	  
			
	4.	 	Notice of Grant	  	 	8	  
			
	5.	 	EMI Options: Limit for individual Eligible Employee	  	 	9	  
			
	6.	 	Overall limits for Company on the Grant of Options	  	 	9	  
			
	7.	 	Ordinary Share Capital	  	 	9	  
			
	8.	 	Non-Transferable	  	 	9	  
			
	9.	 	Rights to Exercise Options	  	 	10	  
			
	10.	 	Exercise of Options	  	 	11	  
			
	11.	 	Lapse of Options	  	 	12	  
			
	12.	 	Takeover, Reconstruction, Liquidation and Sale of the Business	  	 	13	  
			
	13.	 	Replacement Options	  	 	15	  
			
	14.	 	Loss of Office or Employment	  	 	17	  
			
	15.	 	Adjustments	  	 	18	  
			
	16.	 	General	  	 	18	  
			
	17.	 	Overseas Employees	  	 	20	  
			
	18.	 	Supplementary Provisions	  	 	20	  
		
	SCHEDULE 1	  	 	21	  
		
	SCHEDULE 2	  	 	24	  
		
	SCHEDULE 3	  	 	25	  
		
	SCHEDULE 4	  	 	26	  

  
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	1.	Interpretation and Construction 

  

	1.1	Definitions 

 In the Rules, unless the context requires otherwise, the following words
and expressions are defined or otherwise explained by the provisions indicated: 
  

	 “Acquiring Company” 
	any company which has obtained Control of the Company in accordance with any of the provisions of Rule 12; 

  

	 “Adoption Date” 
	the date on which the Rules are adopted by the Directors; 

  

	 “Bad Leaver” 
	any director or employee of any Group Company who ceases to be a director or employee without becoming a director or employee of any other Group Company and is not a Good Leaver; 

 

	 “Committed Time” 
	the meaning given by paragraph 26 of Schedule 5; 

  

	 “Companies Act” 
	the Companies Act 2006; 

  

	 “Company” 
	Mimecast Limited (registered number 04698693) whose registered address is at 2-8 Balfe Street, London, N1 9EG; 

  

	 “Control” 
	the meaning given by section 995 of the Tax Act; 

  

	 “Date of Grant” 
	the date on which an Option is granted to an Employee; 

  

	 “Directors” 
	the board of Directors of the Company or a duly authorised committee thereof; 

  

	 “Disqualifying Event” 
	the meaning given by Sections 534 to 536 of ITEPA; 

  

	 “Eligible Employee” 
	any person who is an employee of the Company or any Qualifying Subsidiary PROVIDED THAT where an Option is intended to be an EMI Option the Employee is an individual; 

 

	 	(a)	whose Committed Time amounts to at least 25 hours a week, or if less, 75% of his Working Time; and 

  

	 	(b)	who does not have a Material Interest in any Group Company; 

  

	 “EMI” 
	Enterprise Management Incentive; 

  

	 “EMI Option” 
	any right to acquire Shares: 

  

	 	(a)	in relation to which the requirements of Schedule 5 are met at the Date of Grant; and 

  
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	 	(b)	of which Notice of Grant is given to HM Revenue & Customs in accordance with paragraph 44 of Schedule 5; 

  

	 	and, where the circumstances permit, a Replacement Option in relation to that EMI Option; 

  

	 “Employee” 
	any individual who is an employee of a Group Company; 

  

	 “Employer Company” 
	the company by reference to which the Option Holder is an Eligible Employee or Employee; 

  

	 “Employer’s NICs” 
	secondary Class 1 national insurance contributions; 

  

	 “Exercise Conditions” 
	any performance conditions set by the Directors under rule 3.4; 

  

	 “Exercise Period” 
	the period during which an Option may be exercised, which in any event shall terminate no later than the day before the 10th anniversary of the Date of Grant; 

 

	 “Good Leaver” 
	any director or any employee of any Group Company who ceases to be a director or employee without becoming a director or employee of any other Group Company by reason of injury or disability or in any other circumstance where the Directors, in
their absolute discretion, determine the director or employee to be a Good Leaver; 

  

	 “Group” and “Group Company”  
	“group”, in relation to a Parent Company, means that company and its Subsidiaries and “Group Company” shall be construed accordingly; 

  

	 “Independence Requirement” 
	the meaning given by paragraph 9 of Schedule 5; 

  

	 “ITEPA” 
	the Income Tax (Earnings and Pensions) Act 2003; 

  

	 “Market Value” 
	shall be determined in accordance with Part VIII of the Taxation of Chargeable Gains Act 1992; 

  

	 “Material Interest” 
	the meaning given by paragraph 29 of Schedule 5; 

  

	 “Notice of Exercise” 
	a notice of exercise in accordance with the form set out in Schedule 2 of the Rules or such other form as may be prescribed or required by the Directors from time to time; 

 

	 “Notice of Grant” 
	the notice of grant of the EMI Option issued by the Employer Company to HM Revenue & Customs in accordance with Rule 4.1; 

  

	 “Option” 
	a right to acquire Shares which shall include an EMI Option or an Unapproved Option; 

  
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	 “Option Agreement” 
	an agreement between the Company and an Eligible Employee (or the Company and an Employee) which shall evidence the grant of the Option, which shall be in accordance with the Rules of the Scheme and which shall be in such form as may be
prescribed by the Directors; 

  

	 “Option Holder” 
	an Eligible Employee who has been granted an EMI Option or an Employee who has been granted an Unapproved Option (or his legal personal representatives where the circumstances permit); 

 

	 “Option Price” 
	the price per Share determined by the Directors which shall not be less than the Market Value of a Share on the Date of Grant and, in the case of an Option which is a right to subscribe for Shares, not less than the nominal value of a Share;

  

	 “Ordinary Share Capital” 
	the meaning given by section 989 of the Tax Act; 

  

	 “Parent Company” 
	a company that has one or more Subsidiaries; 

  

	 “Personal Representatives” 
	in relation to an Option Holder, the Option Holder’s legal personal representatives (being either the executors of his will to whom a valid grant of probate has been made or the duly appointed administrators of his estate) who in either
case have provided the Directors with satisfactory evidence of their appointment; 

  

	 “Qualifying Exchange” 
	an exchange of Shares in accordance with Rule 13.3; 

  

	 “Qualifying Subsidiary”  
	the meaning given by paragraph 11 of Schedule 5 to ITEPA; 

  

	 “Relevant Company” 
	the company (being either the Company or any Group Company) which incurs a Tax Liability as set out in Rule 10.4; 

  

	 “Replacement Option” 
	an Option granted in accordance with Rule 13; 

  

	 “Restrictions” 
	any condition attaching to the Shares which makes the interest in the Shares restricted within the meaning of Chapter 2 of Part VII of ITEPA; 

  

	 “Rules” 
	these rules together with any schedules or appendices to these rules; 

  

	 “Sale of the Business” 
	any transfer (whether through a single transaction or a series of transactions) of all or substantially all of the assets or undertaking of the Group (including goodwill) to any person (or persons connected with each other or act in concert with
each other); 

  

	 “Scheme” 
	this scheme as governed by the Rules; 

  

	 “Scheme of Reconstruction” 
	the meaning given by Rule 12.3; 

  
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	 “Section 431 Election” 
	means an election in accordance with Section 431 of ITEPA being in the form as set out in Schedule 4 to this Scheme or in such other form as HM Revenue & Customs may determine from time to time; 

 

	 “Share” 
	Ordinary Shares in the capital of the Company (and in the context of an EMI Option, which satisfies the requirements of paragraph 35 of Schedule 5); 

  

	 “Schedule 5” 
	Schedule 5 to ITEPA; 

  

	 “Subsidiary”  
	means any body corporate which is a subsidiary of the Company within the meaning of section 1159 of the Companies Act 2006. 

  

	 “Tax Liability” 
	a liability to account for any employee’s tax, national insurance, social security or other levies in respect of the Option (including Employer’s NICs or equivalent employer’s social security contributions) (whether by reason of
grant, exercise, or otherwise or by reason of a Disqualifying Event in relation to EMI Options only), including for the avoidance of doubt and without limitation any liability arising after the termination of the Option Holder’s employment for
whatever reason and which: 

  

	 	(a)	may arise or be incurred in any jurisdiction whatsoever and, 

  

	 	(b)	by the law of the same jurisdiction may or shall be recovered from the person entitled to the Option; 

  

	 “Tax Act” 
	the Income Tax Act 2007; 

  

	 “Trading Activities Requirement” 
	the meaning given by paragraph 13 to 14 of Schedule 5; 

  

	 “Unapproved Options” 
	any right to acquire Shares granted pursuant to this Scheme which does not satisfy the requirements of Schedule 5; 

  

	 “Unvested” 
	such number or the proportion of the Shares subject to an Option that are not Vested; 

  

	 “Vested” 
	such number or the proportion of the Shares subject to an Option that shall become vested according to the Vesting Schedule and “Vest” shall be construed accordingly; 

 

	 “Vesting Schedule” 
	unless otherwise specified in the schedule in the Option Holder’s Option Agreement the Vesting Schedule shall be as follows: 

  

	 	 25% of the Options shall be vested on the first anniversary of the Date of Grant and thereafter 6.25% of the Options shall vest at the expiry of 3 months from

  
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such anniversary and at the expiry of every subsequent 3 months period until the Options are fully vested on the fourth anniversary of the Date of Grant. 

 

	 “Working Time” 
	the meaning given by paragraph 27 of Schedule 5; 

  

	 “Year” 
	a financial year of the Company. 

  

	1.2	Construction 

 Words or expressions used herein shall where appropriate: 

 

	 	(a)	when denoting the masculine gender include the feminine and vice-versa; 

  

	 	(b)	when denoting the singular include the plural and vice versa; 

  

	 	(c)	when referring to any enactment be construed as a reference to that enactment as for the time being consolidated, amended, re-enacted or replaced and shall include any regulations made thereunder; 

 

	 	(d)	when a period of time is specified and starts from a given day or the day of an act or event, be calculated exclusive of that day; and 

 

	 	(e)	be construed such that the headings and sub-headings are for ease of reference only, and do not affect the interpretation of any Rule; 

 

	 	(f)	be construed where not otherwise defined in the Rules to have the same meanings as in Schedule 5. 

  

	2.	Statement of Purpose 

 EMI Options granted at any time pursuant to the Rules are granted
for commercial reasons in order to recruit or retain an Eligible Employee and not as part of a scheme or arrangement the main purpose, or one of the main purposes, of which is the avoidance of tax. 

 

	3.	Grant of Options 

  

	3.1	General 

  

	 	(a)	Subject to the Rules, the Company may, at any time, grant 

  

	 	(i)	any Eligible Employee an EMI Option; or 

  

	 	(ii)	any Employee an Unapproved Option 

 over such number of Shares at such Option Price and with
such conditions of exercise as the Company may determine. 
  

	 	(b)	An EMI Option shall be granted in accordance with the provisions of Schedule 5. 

  

	 	(c)	EMI Options shall only be granted to individuals who are Eligible Employees. 

  
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	 	(d)	Unapproved Options shall only be granted to individuals who are Employees. 

  

	 	(e)	An Option shall not be granted by any person other than the Company without the prior approval of the Directors. 

  

	3.2	Contents of Option Agreement 

 The Option shall be agreed in writing between the Company
and the Option Holder, and shall state: 
  

	 	(a)	the Date of Grant; 

  

	 	(b)	that the EMI Option is granted under the provisions of Schedule 5; 

  

	 	(c)	the number or maximum number of Shares over which the Option is granted; 

  

	 	(d)	the Option Price, or the method by which the Option Price is to be determined; 

  

	 	(e)	the Vesting Schedule; 

  

	 	(f)	the Exercise Period and; 

  

	 	(g)	details of any Restrictions attaching to the Shares and, if so, shall contain details of such Restrictions. 

  

	3.3	The Option Agreement for an Unapproved Option shall be in the same form as Rule 3.2 apart from Rule 3.2(b) and (g) which shall not apply. 

 

	3.4	The Directors may at the Date of Grant impose such performance condition or performance conditions to be satisfied upon the exercise of an Option. Such performance conditions: 

 

	 	(a)	must be objective and stated in writing at the Date of Grant; 

  

	 	(b)	may not be waived, varied or amended by the Directors unless in accordance with the terms of such conditions or, where any waiver, variation or amendment is at the discretion of the Directors, it shall only be exercised
in a manner which the Directors have determined to be fair and reasonable and, if events happen which cause the Directors, acting fairly and reasonably, to consider that the waived, varied or amended condition would be appropriate and would result
in the waived, varied or amended condition being no easier and no more difficult to satisfy than the condition as it existed immediately prior to such waiver, variation or amendment. 

 

	4.	Notice of Grant 

  

	4.1	On the grant of an EMI Option, a Notice of Grant shall be given by the Employer Company to HM Revenue & Customs within 92 days of the Date of Grant (or such further or other period as HM Revenue &
Customs or statute may allow, permit or require) and shall: 

  

	 	(a)	be in the form set out in Schedule 3 of the Rules or in such form as required by HM Revenue & Customs from time to time; 

  

	 	(b)	contain a declaration by the Option Holder that he satisfies the Working Time requirement; 

  
 8 

	 	(c)	contain a declaration by a director or the secretary of the Employer Company that: 

  

	 	(i)	in his opinion the requirements of Schedule 5 are met; and 

  

	 	(ii)	the information provided is to the best of his knowledge correct and complete. 

  

	4.2	On the grant of an Unapproved Option a Notice of Grant shall not be required. 

  

	5.	EMI Options: Limit for individual Eligible Employee 

  

	5.1	The number of Shares over which an EMI Option may be granted to any one Eligible Employee shall be limited and take effect so that the total value of Shares (as determined by paragraphs 5(6) to (8) of Schedule 5)
subject to unexercised EMI Options granted to that Eligible Employee by the Company or any other Group Company does not exceed £1 less than £120,000 (or such other limit as may apply from time to time in paragraph 5 of Schedule 5), SAVE
WHERE an EMI Option is granted under the provisions of Part 6 (Company Reorganisation) of Schedule 5. 

  

	5.2	Provided that if an EMI Option exceeds the limit in Rule 5.1 the Option shall be treated as two Options, one shall be an EMI Option as to the number of Shares to the value of £1 less than the limit in Rule 5.1 and
the other Option relating to the excess shall be an Unapproved Option. 

  

	6.	Overall limits for Company on the Grant of Options 

  

	6.1	Subject to such adjustments as may be made in accordance with Rule 15, no Option shall be granted on any Date of Grant if as a result the total value of Shares of the Company (as determined by paragraphs 5(6) to
(8) of Schedule 5) in respect of which unexercised EMI Options exist would exceed £3 million or such other limit as may apply from time to time in paragraph 7 of Schedule 5. 

 

	6.2	For the purpose of the limit contained in Rule 6.1 above, any Option or right which has been released, cancelled or lapsed without being exercised shall be ignored. 

 

	6.3	If following the purported grant of an EMI Option the limit in Rule 6.1 would be exceeded such an Option shall not be an EMI Option insofar as it relates to the excess. 

 

	7.	Ordinary Share Capital 

  

	7.1	Availability of authorised capital and Shares 

 The Company shall at all times keep
available sufficient authorised and unissued Shares to satisfy the exercise to the full extent still possible of all Options which have neither lapsed nor been fully exercised taking account of any other obligations of the Company to provide shares
of the same class as Shares. 
  

	8.	Non-Transferable 

 Save as provided in Rule 9.4, no Option nor any right thereunder shall
be capable of being transferred, assigned or charged in any manner whatsoever. Upon any such purported transfer, assignment, or charge the Option shall immediately lapse and cease to be exercisable. 

  
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	9.	Rights to Exercise Options 

  

	9.1	General 

 Subject to rules 9.2, 9.3, 9.4, 9.5 and 12 below an Option: 

 

	 	(a)	shall not be exercisable before it has Vested in accordance with the Vesting Schedule; and 

  

	 	(b)	shall not be exercisable until an exit event set out in rule 12, subject to the provisions of the Option Agreement and subject to the provisions in rule 12.3; 

 

	 	(c)	shall not be exercisable unless the Exercise Conditions (if any) (as waived, varied or amended) have been fulfilled to the satisfaction of the Directors; and 

 

	 	(d)	shall not be exercised later than the day before the tenth anniversary of the Date of Grant. 

  

	9.2	Termination of Employment 

 If the Option Holder is a Bad Leaver, the Option, whether
Vested and unexercised or Unvested shall lapse immediately on the date upon which the Option Holder ceases to hold employment or office within the Group, or in the case of gross misconduct, on the date of occurrence of such misconduct. 

 

	9.3	Good Leaver 

 If the Option Holder is a Good Leaver: 

 

	 	(a)	the Option shall be exercisable to the extent Vested as at the date of ceasing employment within 39 days of ceasing employment (provided that the Directors shall have the discretion to waive the Exercise Conditions (if
any) relating to such Option); 

  

	 	(b)	the Option to the extent Unvested shall lapse immediately on the date upon which the Option Holder ceases employment, unless the Directors in their discretion determine before cessation that the Unvested Option may be
exercised within 39 days of ceasing employment. 

  

	9.4	Death of the Option Holder 

 If an Option Holder dies, the Option shall be exercisable to
the extent Vested as at the date of the Option Holder’s death by the Personal Representatives, provided that the Option shall only be exercisable within 12 months of the Option Holder’s death (and provided that the Directors shall have the
discretion to waive the Exercise Conditions (if any) relating to such Option). To the extent that the Option is Unvested the Option shall lapse on the date of the Option Holder’s death. 

 

	9.5	Admission to Main Market of London Stock Exchange or AIM 

 If the Company’s shares
are admitted to listing on the Main Market of the London Stock Exchange, AIM or any other securities exchange, the Option shall Vest in full immediately after the admission date (notwithstanding that part of the Option may be Unvested). The Option
will be exercisable (subject to the discretion of the Board to permit an earlier exercise) as follows: 
  

	 	(a)	25% immediately following the admission date; 

  
 10 

	 	(b)	a further 50% on the first anniversary of the admission date; 

  

	 	(c)	a further 25% on the second anniversary of the admission date. 

  

	10.	Exercise of Options 

  

	10.1	Procedure on exercise 

 An Option shall be exercisable, in whole or in part, by the
delivery to the secretary of the Company of the following: 
  

	 	(a)	an Option Agreement covering all of the Shares over which the Option is then to be exercised; 

  

	 	(b)	the Notice of Exercise in the prescribed form duly completed and signed by the Option Holder (or by his duly authorised agent); 

  

	 	(c)	a Section 431 Election (or a similar election should the Directors so require); 

  

	 	(d)	payment (in such manner as the Directors shall permit) of a sum equal to the aggregate Option Price for the number of Shares over which the Option is to be exercised; 

 

	 	(e)	payment (in such manner as the Directors shall permit) of any Tax Liability including Employer’s NICs in accordance with Rule 10.4; and 

 

	 	(f)	if there is a shareholders’ agreement or other such document (which contains restrictions on the Shares), is accompanied by a deed of adherence, in a form acceptable to the Company and executed by the Option
Holder, whereby the Option Holder agrees to be bound by the terms of such shareholders’ agreement or other such document. 

  

	10.2	Issue or transfer of Shares 

 The Company shall issue or procure the transfer of
Shares to be allotted or transferred pursuant to the exercise of an Option to the Option Holder such number of Shares within 30 days following the effective date of exercise of the Option. 

 

	10.3	Shares issued pursuant to the Scheme will rank pari passu in all respects with the Shares then already in issue except that they and any Shares transferred pursuant to the Scheme will not rank for any dividend or other
distribution of the Company paid or made by reference to a record date falling prior to the date of receipt of the Notice of Exercise of the Option pursuant to Rule 10.1. 

 

	10.4	Deductions 

  

	 	(a)	Where in relation to Options, the Company or any Group Company (“the Relevant Company”) is liable, or is in accordance with current practice believed to be liable under any statute or regulation or otherwise,
to account to any revenue or other authority for sums in respect of a Tax Liability in relation to the Option, the Option Holder shall indemnify and shall keep indemnified the Relevant Company for the Tax Liability and the Option Holder shall pay
the Relevant Company a sum equal to the Tax Liability immediately upon written notice of the quantum of the said liability. 

  

	 	(b)	 Notwithstanding the above, the Company may impose such conditions upon the exercise of the Options as are necessary to ensure that the Relevant

  
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Company is able to meet any or all of such liabilities, including, without limitation, a condition that no exercise may take place unless the Option Holder has provided the Relevant Company with
cash funds sufficient to meet such Tax Liability, or has entered into arrangements acceptable to the Relevant Company to secure that such cash funds are available, or to allow the Relevant Company to deduct the amount of such Tax Liability from any
cash amounts (including salary and bonuses) which may become payable to the Option Holder by any Group Company. 

  

	 	(c)	The Company may require the Option Holder as a condition of the exercise of any Option that the Option Holder shall: 

  

	 	(i)	agree to reimburse the Relevant Company for any Employer’s NICs arising on the exercise of an Option; or 

  

	 	(ii)	enter into an election with the Relevant Company to assume the liability for any Employer’s NICs, payable on the exercise of the Option, including an election under paragraph 3B of Schedule 1 to the Social Security
Contributions and Benefits Act 1992; OR 

  

	 	(iii)	agree to pay the employer’s social security contributions, to the extent permitted by law, in any other jurisdiction. 

  

	 	(d)	If the Option Holder shall fail to: 

  

	 	(i)	make payment to the Relevant Company immediately upon receipt of a written notice in accordance with Rule 10.4(a); or 

  

	 	(ii)	reimburse the Relevant Company in accordance with an agreement or election in whole or in part for any liability to employer’s secondary national insurance contributions or employer’s social security
contributions pursuant to Rule 10.4(c); 

 then the Company shall be authorised by the Option Holder to reduce the number of
Shares otherwise deliverable to the Option Holder upon the exercise of an Option as may be sufficient to produce a sum which (after allowance for the costs and expenses of such a sale) may discharge (and shall be applied in discharge of) the Option
Holder’s liability to the Relevant Company under Rule 10.4(a) or any agreement or election pursuant to Rule 10.4(c) and the Company may exercise all such powers and may appoint any of its officers to sign all such documents in the name of the
Option Holder and as his act and deed as may be necessary for this purpose. 
  

	 	(e)	If the Option Holder shall fail to make payment to the Relevant Company immediately upon receipt of a written notice in accordance with Rule 10.4(a) then the Option Holder shall be liable to make good any amount
outstanding on demand. 

  

	11.	Lapse of Options 

  

	11.1	General 

 An Option shall immediately cease to be exercisable and shall lapse on the
earliest of: 
  

	 	(a)	the tenth anniversary of the Date of Grant; 

  
 12 

	 	(b)	the date upon which the Option Holder ceases to hold employment or office within the Group if the Option Holder is a Bad Leaver; 

  

	 	(c)	the expiry of the period in Rule 9.3, except that if the Option Holder dies during the exercise period specified in Rule 9.3, an Option shall not lapse by reason of this Rule 11.1 (c) until the first anniversary of
the Option Holder’s death, if later; 

  

	 	(d)	the first anniversary of the Option Holder’s death; 

  

	 	(e)	subject to Rule 13.1, the expiry of any of the periods referred to in Rule 12; 

  

	 	(f)	the date on which it is purported to be transferred or assigned (other than by reason of death in accordance with Rule 9.4), mortgaged, charged or otherwise disposed of by the Option Holder; 

 

	 	(g)	the presentation of any petition to any court of competent jurisdiction by which an order is sought for the bankruptcy of the Option Holder; 

 

	 	(h)	upon the Option Holder making an application for an interim order or any proposal for a voluntary arrangement within Part VIII of the Insolvency Act 1986; 

 

	 	(i)	upon the Option Holder proposing any form of compromise with his creditors or any class of creditors; and 

  

	 	(j)	the date on which the Option Holder is deprived (otherwise than on death) of the legal or beneficial ownership of the Option by operation of law or by the Option Holder doing or omitting to do anything which causes him
to be so deprived. 

  

	12.	Takeover, Reconstruction, Liquidation and Sale of the Business 

  

	12.1	General Offer 

 If any person obtains Control of the Company as a result of: 

 

	 	(a)	making an offer to acquire the whole of the issued share capital of the Company which is made on a condition such that, if it is satisfied, the person making the offer will have Control of the Company; or

  

	 	(b)	negotiating a share sale and purchase agreement with the shareholders of the Company which contemplates that the person will obtain Control of the Company on completion; 

(“a General Offer”), an Option may be exercised in accordance with the provisions in rule 12.3, to the extent Vested and to the
extent that the Exercise Conditions (if any) have been satisfied (and 75% of the Unvested Option shall be regarded as Vested and the remaining 25% of the Unvested Option may only be exercisable if the Directors determine that the circumstances
justify the exercise of a larger proportion than 75% of the Unvested Option). 
  

	12.2	Control 

 For the purposes of Rule 12.1 a person shall be deemed to have obtained Control
of the Company if he and others acting in concert with him have together obtained Control of it. 

  
 13 

	12.3	Exercise period for options and the offer of Replacement Options on a takeover 

  

	 	(a)	If Replacement Options are offered to all Option Holders by the Acquiring Company in relation to the Vested Options (including the Options which have been Vested due to the Change of Control) and an Option Holder does
not agree to release the Vested Options and accept the Replacement Option, the Board shall determine whether such Vested Options shall be exercisable in accordance with rule 12.3 (d) below or whether such Vested Options shall lapse.

  

	 	(b)	If Replacement Options are offered to all Option Holders by the Acquiring Company in relation to the Vested Options (including the Options which have been Vested due to the Change of Control) and an Option Holder does
agree to release the Vested Options and accept the Replacement Option, the terms of rule 13 shall apply to the Replacement Option. 

  

	 	(c)	If Replacement Options are not offered to all Option Holders then the Vested Options shall be exercisable in accordance with rule 12.3 (d) below. 

 

	 	(d)	In the circumstances set out in this rule 12.3, the Vested Options can be exercised in either of the following exercise periods determined by the Directors: - 

 

	 	(i)	Immediately before the change of Control becoming unconditional; or 

  

	 	(ii)	During a one month exercise period starting at a date to be determined by the Directors but such period to take place before the expiry of the 12 months period commencing on the change of Control becoming unconditional.

  

	12.4	Scheme of Reconstruction 

 If any person obtains Control of the Company in pursuance of a
compromise or arrangement sanctioned by the court under section 900 of the Companies Act or Article 418 of the Companies (Northern Ireland) Order 1986 (“a Scheme of Reconstruction”), an Option may be exercised to the extent Vested (and may
only be exercised to the extent Unvested if the Board in its discretion permits exercise) within 39 days of the court sanctioning the Scheme of Reconstruction. An Option shall not be exercisable after the said 39 days but may still be released under
Rule 13 within the period of six months following the court sanction of the Scheme of Reconstruction and, on the expiry of the said six month period, the Option shall lapse. 
  

	12.5	Chapter 3, Part 28 of the Companies Act 

 If any person becomes bound or entitled to
acquire shares under Chapter 3, Part 28 of the Companies Act, an Option may be exercised to the extent Vested (and may only be exercised to the extent Unvested if the Board in its discretion permits exercise) at any time when that person remains so
bound or entitled. 
  

	12.6	Liquidation 

 If a general meeting of the Company is called at which it is proposed to
pass a resolution for the voluntary winding up of the Company, the Company shall notify the Option Holder as soon as practicable of this fact. The Option may be exercised to the extent Vested (and may only be exercised to the extent Unvested if the
Board in its discretion permits exercise) during the period of such notice (such exercise being conditional on such resolution being passed and taking effect immediately thereafter) 

  
 14 

 
and such portion of the Option not otherwise exercised before such resolution has been passed shall thereupon lapse. Where the Option Holder has exercised the Option pursuant to this Rule 12.6
and the resolution referred to above has been passed then (subject to the consent of the Company’s liquidator where such is required by section 88 of the Insolvency Act 1986) the exercise of the Option shall take effect immediately and the
Option Holder shall be entitled to share in the assets of the Company with the existing shareholders in the same manner as the Option Holder would have been entitled had the Option Holder been the registered owner of the relevant Shares before the
resolution was passed. 
  

	12.7	Reorganisation 

 An option may not be exercised under rule 12.1 if the General Offer is
part of a reorganisation so that the shareholders of the Acquiring Company hold their shares in the Acquiring Company in the same proportions as they held their shares in the Company. 

 

	12.8	Sale of Business 

 An Option may be exercised to the extent Vested (and may only be
exercised to the extent Unvested if the Board in its discretion permits exercise) within 39 days of a Sale of the Business and the Company shall notify the Option Holder as soon as practicable of this fact. 

 

	13.	Replacement Options 

  

	13.1	Grant of Replacement Options 

 If any company (“the Acquiring Company”): 

 

	 	(a)	obtains Control of the Company as a result of making a General Offer in accordance with Rule 12.1; or 

  

	 	(b)	obtains Control of the Company as a result of a Scheme of Reconstruction in accordance with Rule 12.3; or 

  

	 	(c)	becomes bound or entitled to acquire the Shares under Chapter 3, Part 28 of the Companies Act in accordance with Rule 12.4, or 

  

	 	(d)	obtains all the Shares as a result of a Qualifying Exchange within Rule 13.3, 

 an Option Holder
may at any time within the period set out in Rule 13.2, by agreement with the Acquiring Company, release any Option which has not lapsed (“the Old Option”) in consideration of the grant to him of an Option (“the New Option”)
which is equivalent to the Old Option but relates to shares in the Acquiring Company and qualifies as a Replacement Option as set out in rules 13.4 and 13.5. 
  

	13.2	Period within which Replacement Option to be granted 

 The New Option must be granted
within the following periods: 
  

	 	(a)	if the change of Control is by reason of a general offer in accordance with Rule 12.1, the period of six months beginning with the time when the person making the offer has obtained control of the Company and any
condition subject to which the offer is made is satisfied; 

  
 15 

	 	(b)	if the change of Control is by reason of a Scheme of Reconstruction (in accordance with Rule 12.3) or a Qualifying Exchange the period of six months beginning with the time when the Acquiring Company obtains Control of
the Company whose shares are subject to the Old Option; 

  

	 	(c)	if the change of Control occurs under Chapter 3, Part 28 of the Companies Act, the period during which the Acquiring Company remains bound or entitled in accordance with those procedures. 

 

	13.3	Exchange of Shares 

  

	 	(a)	An exchange of shares will be treated as a Qualifying Exchange where arrangements are made in accordance with which a company (“the New Company”) acquires all the shares (“Old Shares”) in another
company (“the Old Company”) and the following conditions are met: 

  

	 	(i)	that the consideration for the Old Shares consists wholly of the issue of shares (“New Shares”) in the New Company; 

  

	 	(ii)	that New Shares are issued in consideration of Old Shares only at times when there are no issued shares in the New Company other than: 

 

	 	(A)	subscriber shares, and 

  

	 	(B)	New Shares previously issued in consideration of Old Shares; 

  

	 	(iii)	that the consideration for New Shares of each description consists wholly of Old Shares of the corresponding description; 

  

	 	(iv)	that New Shares of each description are issued to the holders of Old Shares of the corresponding description in respect of, and in proportion to, their holdings; and 

 

	 	(v)	that by virtue of section 127 of the Taxation of Chargeable Gains Act 1992 as applied by section 135(3) of that Act, the exchange of shares is not treated as involving a disposal of the Old Shares or an acquisition of
the New Shares. 

  

	 	(b)	For the purposes of this rule Old Shares and New Shares are of a corresponding description if, on the assumption that they were shares in the same company, they would be of the same class and carry the same rights, and
references to “shares”, except in the expression “subscriber shares”, includes securities. 

  

	13.4	Qualifying requirements for Replacement Option 

 Subject to Rule 13.5, a New Option
qualifies as a Replacement Option only if: 
  

	 	(a)	the New Option is granted to the Option Holder by reason of his employment: 

  

	 	(i)	with the Acquiring Company, or 

  

	 	(ii)	if that company is a Parent Company, with that company or another Group Company; 

  

	 	(b)	at the time of the release of rights under the Old Option, the purpose for granting the New Option is for commercial reasons in order to recruit or retain an Eligible Employee, and not as part of a scheme or arrangement
the main purpose, or one of the main purposes, of which is the avoidance of tax; 

  
 16 

	 	(c)	at that time, 

  

	 	(i)	the Independence Requirement and the Trading Activities Requirement are met in relation to the Acquiring Company; 

  

	 	(ii)	the individual to whom the New Option is granted is an Eligible Employee in relation to the Acquiring Company; and 

  

	 	(iii)	the New Option would satisfy the requirements of being an EMI Option set out in Part V of Schedule 5; 

  

	 	(d)	the total Market Value, immediately before the release, of the Shares which were subject to the Old Option is equal to the total Market Value, immediately after the grant, of the Shares in respect of which the New
Option is granted; and 

  

	 	(e)	the total amount payable by the employee for the acquisition of shares in pursuance of the New Option is equal to the total amount that would have been payable for the acquisition of shares in pursuance of the Old
Option. 

  

	13.5	Provided that a Replacement Option for an Unapproved Option shall not have to satisfy the requirements in Rule 13.4(b) and Rule 13.4(c). 

 

	13.6	Where, in accordance with this Rule 13, an Option is released and a New Option granted, the New Option shall not be exercisable in accordance with Rule 12 by virtue of the event which gave rise to the New Option being
granted. 

  

	14.	Loss of Office or Employment 

  

	14.1	The grant of an Option does not form part of the Option Holder’s entitlement to remuneration or benefits pursuant to his contract of employment nor does the existence of a contract of employment between an Eligible
Employee and any company give such Eligible Employee any right or entitlement to have an Option granted to him in respect of any number of Shares or any expectation that an Option might be granted to him whether subject to any conditions or at all
and the grant of an Option shall not give him any entitlement or expectation that further Options will be granted. 

  

	14.2	The rights and obligations of an Option Holder under the terms and conditions of his office or employment shall not be affected by his participation under the Rules or any right he may have to participate.

  

	14.3	An individual who participates under the Rules waives all and any rights to compensation or damages in consequence of the termination of his office or employment with any company for any reason whatsoever, whether
lawful or not, in so far as those rights arise, or may arise, from his ceasing to have rights under or be entitled to exercise any Option under the Rules as a result of such termination or from the loss or diminution of value of such rights or
entitlements. If necessary, the Option Holder’s terms of employment shall be varied accordingly. 

  
 17 

	15.	Adjustments 

  

	15.1	General rule 

 The number of Shares over which an Option is granted and the Option Price
thereof shall be adjusted in such manner as the Directors shall determine following any capitalisation issue, rights issue, subdivision, consolidation or reduction of share capital of the Company or any other variation of share capital to the intent
that (as nearly as may be) the total Option Price multiplied by the number of Shares that is payable in respect of an Option shall remain unchanged. 
  

	15.2	Reduction of Option Price to below nominal value 

 Subject to Rule 15.3 below, an
adjustment may be made under Rule 15.1 above which would have the effect of reducing the Option Price of unissued shares to less than the nominal value of a Share, but only if, and to the extent that, the Directors shall be authorised to capitalise
from the reserves of the Company a sum equal to the amount by which the aggregate nominal value of the Shares in respect of which the Option is exercisable exceeds the aggregate adjusted Option Price, so that on exercise of any Option in respect of
which the Option Price has been reduced, the Directors shall capitalise and apply such sum (if any) as is necessary to pay up the amount by which the aggregate nominal value of the Shares in respect of which the Option is exercised exceeds the
aggregate Option Price for such Shares. 
  

	15.3	Option over issued and unissued Shares 

 Where an Option subsists over both issued and
unissued Shares, an adjustment permitted by Rule 15.2 above, may only be made if the reduction of the Option Price of both issued and unissued Shares can be made to the same extent. 

 

	15.4	Administrative steps 

 The Directors shall notify Option Holders of any adjustment made
under this Rule 15 as soon as reasonably practicable and may take such steps and the Company shall execute such documents as it considers necessary to give effect to such adjustment. Furthermore, and without limitation to the generality of the
foregoing, the Directors may call in, cancel, endorse, issue or reissue any Option Agreement subsequent upon such adjustment. 
  

	16.	General 

  

	16.1	Amendments 

  

	 	(a)	Subject to rules 16.1(b) to (d), the Directors shall have the discretion to: 

  

	 	(i)	amend or add to the Rules; and 

  

	 	(ii)	impose additional conditions or requirements on the Options or on the terms on which Shares are acquired. 

  

	 	(b)	No amendments may be made to the Rules which would have the effect of causing EMI Options to cease to be EMI Options. 

  

	 	(c)	The Directors may at any time make such alterations (including additions) to the Rules as are necessary to secure that the Rules as applicable to EMI Options are in accordance with Schedule 5 and continue to be in
accordance with Schedule 5. 

  
 18 

	 	(d)	No amendment or addition shall be made to the Rules which would abrogate or adversely affect the subsisting rights of Option Holders unless: 

 

	 	(i)	where the rights are enjoyed by a single Option Holder and are not enjoyed by any other Option Holder or class of Option Holders, it is made with the written consent of that Option Holder; or 

 

	 	(ii)	where the rights are enjoyed by all Option Holders or any class of Option Holders then: 

  

	 	(A)	with the consent in writing of such number of Option Holders or class of Option Holders (as the case may be) as hold Options under the Scheme to acquire 75 per cent (75%) of the Shares which would be issued or
transferred if all Options granted and subsisting under the Scheme were exercised; or 

  

	 	(B)	by a resolution at a meeting of Option Holders or class of Option Holders passed by not less than 75 per cent (75%) of the Option Holders who attend and vote either in person or by proxy; 

and for the purpose of this Rule 16.1(d) the Option Holders or any class of Option Holders shall be treated as the holders of a separate class
of share capital and the provisions of the Articles of Association of the Company relating to class meetings shall apply mutatis mutandis. 
  

	16.2	Termination 

 The Scheme shall terminate upon the tenth anniversary of the Adoption Date
or at any earlier time by the passing of a resolution by the Directors. Termination shall be without prejudice to the subsisting rights of Option Holders. 
  

	16.3	Conflict with Schedule 5 

 If there is any conflict between the provisions of the Rules
as they apply to EMI Options and Schedule 5, Schedule 5 shall take precedence in respect of EMI Options. 
  

	16.4	Notices and documents 

  

	 	(a)	Option Holders not otherwise entitled thereto may at the discretion of the Company be sent copies of notices and other documents sent by the Company to its ordinary shareholders generally. 

 

	 	(b)	Written notice of any amendment made in accordance with this Rule 16 shall be given to those Option Holders affected by such amendment. 

 

	 	(c)	Any notice or other document required to be given hereunder to any Option Holder shall be delivered to him or sent by first class pre-paid post to him at his home address according to the records of the Company or such
other address as may appear to the Directors to be appropriate. Any notice or other document required to be given to the Directors shall be delivered to the Directors or sent by first class pre-paid post to the Directors at the Company’s
registered office or such other address as may be determined by the Directors to be appropriate. Notices sent by post to an Option Holder shall be deemed to have been given on the fifth day following the date of posting. 

  
 19 

	16.5	Disputes 

 The decision of the Directors in any dispute or question relating to any
Option shall be final and conclusive subject to the terms of this Scheme. 
  

	16.6	Governing Law 

 The Rules shall be governed by and construed in accordance with English
law. 
  

	16.7	Contracts (Rights of Third Parties) Act 1999 

 Except as expressly provided by the
Company, a person who is not the Option Holder or a Company who is not a member of the Group has no right under the Contracts (Rights of Third Parties) Act 1999 to rely upon or enforce any provisions of this Scheme, but this does not affect any
right or remedy of a third party which exists or is available apart from that Act. The Option Holder may not declare himself a trustee of his rights under this Scheme for the benefit of any third parties. 

 

	16.8	Data Protection 

 The Company and the Employer Company (if different) from time to time
will collect, hold and process the Option Holder’s personal information for the purposes of the administration of this Option. The Company will not use such personal information for any purpose other than the administration of the Option,
unless the Option Holder’s consent to that use is obtained. 
  

	17.	Overseas Employees 

 Notwithstanding any other provision of the Scheme the Board may
amend or add to the provisions of the Scheme and the terms of Option Agreements it considers necessary or desirable to take account of, or to mitigate, or to comply with relevant overseas taxation, securities or exchange control laws, provided that
the terms of Options granted to such Employees are not more favourable overall than the terms of Awards granted to other Employees. 
  

	18.	Supplementary Provisions 

 The Group shall not be liable to the Option Holder for any tax
or additional tax or national insurance payable by the Option Holder upon the exercise of an Option or upon the subsequent disposal of any Shares acquired upon exercise of the Option being tax or national insurance payable because of a failure to
qualify for relief under sections 529 to 532 of ITEPA in consequence of anything done by the Group. 

  
 20 

 SCHEDULE 1 

OPTION AGREEMENT 
  

	
	THIS DOCUMENT IS IMPORTANT AND SHOULD BE KEPT IN A SAFE PLACE

 THIS OPTION AGREEMENT is made the [●] day of [●] 20     

BETWEEN 
  

	(1)	MIMECAST LIMITED (registered number 04698693) whose registered address is at 2-8 Balfe Street, London, N1 9EG; and 

  

	(2)	[Name] of [Address] (the “Option Holder”) 

 SUPPLEMENTAL to the
rules of the Mimecast Limited 2010 EMI Share Option Scheme (the “Scheme”). Any words or expressions used in this option agreement and defined by the Scheme shall bear the same meaning in this agreement. 

INTRODUCTION: 
  

	(A)	The Company intends to grant an Option to the Option Holder. 

  

	(B)	The Option is intended to be an [EMI option/unapproved option]. 

  

	(C)	[The Option is granted under Schedule 5 ITEPA 2003.] 

 AGREED TERMS 

 

	1.	Grant 

 The Company GRANTS an [EMI option/unapproved option] to the Option Holder
and the Option Holder AGREES to be bound in all respects by the provisions of the Scheme and ACCEPTS the grant on the terms set out in their agreement. 
  

	2.	Terms of the Scheme 

  

	2.1	Under the terms of the Scheme the Option Holder may acquire the number of ordinary shares (“Shares”) in the Company stated in clause 6(a) at the Option price per Share set out in clause 6.1. 

 

	2.2	The Option is granted and exercisable subject to the terms and conditions set out in the Scheme and in this Option Agreement. 

  

	3.	Memorandum and articles 

 Any Shares allotted or transferred pursuant to the exercise of
the Option are subject to the memorandum and articles of association of the Company (as amended from time to time) and to any necessary consents of any governmental or other authorities under any enactments from time to time in force. 

  
 21 

	4.	Non transferable 

 The Option is personal to the Option Holder and is not transferable,
assignable or chargeable. 
  

	5.	Exercise 

 The Option shall not be exercisable on or after the 10th Anniversary of the date of grant of the Original Option. 
  

	6.	Grant 

  

	6.1	The details of the grant are as follows; namely 

  

							
	(a)	  	  Number of Shares subject to the Option	  	      [●].	 	
				
	(b)	  	  Option price per Share	  	      [●].	 	
				
	(c)	  	  Date of grant	  	      [●].	 	
				
	(d)	  	  Vesting Commencement Date	  	      [●].	 	

  

	6.2	The Option Holder irrevocably agrees to reimburse the Relevant Company for any Employer’s NICs arising on the exercise of an Option; or agrees to enter into an election with the Relevant Company to assume the
liability for any Employer’s NICs, payable on the exercise of the Option, including an election under paragraph 3B of Schedule 1 to the Social Security Contributions and Benefits Act 1992. 

 

	6.3	The exercise of the Option shall be conditional upon the Option Holder making good any Tax Liability in relation to the Option, or entering into arrangements acceptable to the Company in respect of such Tax Liability,
in accordance with rule 10.4 of the Scheme. 

  

	6.4	[The exercise of the Option shall be subject to the following Exercise Conditions: 

[                      
                              ] Details] 

  
 22 

 Vesting Schedule 

[            ] 

This option agreement has been executed as a deed and unconditionally delivered on the date first above written. 

 

					
	SIGNED as a DEED	  	)	  	
	By MIMECAST LIMITED acting by    	  	)	  	
			
		  		  	 Director

			
	Signature of Witness:	  		  	
			
	Name of Witness:	  		  	
			
	Address:	  		  	
			
	Occupation:	  		  	
			
	SIGNED as a DEED	  	)	  	
	By [Option Holder]	  	)	  	
			
	Signature of Witness:	  		  	
			
	Name of Witness:	  		  	
			
	Address:	  		  	
			
	Occupation:	  		  	

  
 23 

 SCHEDULE 2 

NOTICE OF EXERCISE 
 TO:
    The Secretary, Mimecast Limited 
 I/We, being the holder or the Personal Representative(s) of the holder,* of the option granted in
the Option Certificate overleaf (“the Option”): 
  

	2.1	hereby exercise the Option to acquire                  ordinary shares in Mimecast Limited (“the Shares”) at a price of
£[●] per ordinary share, subject to the provisions contained in an Option Agreement dated [●] (“the Agreement”) made pursuant to the Mimecast Limited 2010 EMI Share Option Scheme and made between Mimecast Limited
and [●]; 

  

	2.2	enclose a cheque for the total price of the Shares (£            ) in favour of Mimecast Limited (“the Company”) and crossed
“a/c payee”, or such other documentation in respect of bridging finance or undertaking to procure payment as may be agreed by the Directors; 

  

	2.3	authorise and request you to enter my/our name(s) in the Company’s Register of Members as the holder(s) of the Shares, subject to the Company’s Memorandum and articles of association; 

 

	2.4	hereby covenant to pay the Company the amount of any Tax Liability** which may arise as a consequence of or in connection with this exercise of the Option (and, for the purposes of this Notice of Exercise, the
expression “Tax Liability” has the same meaning as it has in the Agreement; 

  

	2.5	in order to give effect to this covenant, I/we hereby authorise and appoint the Company as my/our attorney in my/our name(s) and on my/our behalf: 

 

	 	(a)	to sell such number (but no more) of the Shares registered in my/our name(s) as will enable the Company (after payment of all necessary selling expenses and commissions) to recover and retain for itself from the sale
proceeds an amount equal to such Tax Liability and then account to me/us for any cash balance remaining, provided that the Company may sell that number of shares at such price or prices as it shall, in its absolute discretion, consider fair and
reasonable, and 

  

	 	(b)	generally to sign any stock transfer form or other document or documents which may be required and to do any other thing which the Company shall consider necessary or expedient for carrying out the acts hereby
authorised in the same manner and as fully in all respects as I/we could have done personally and I/we hereby undertake to ratify everything which the Company shall do or purport to do by virtue of this power of attorney; and 

 

	2.6	request you to send a share certificate in respect of the Shares not sold pursuant to the authority given above (and, if appropriate, a balance option certificate) to me/us at the address given below. 

SIGNED and DELIVERED as a DEED BY 
  

									
	Name	 	  
	 		 	Address	 	  

					
	Signature	 	  
	 		 		 	  

					
	Date	 	  
	 		 		 	
					
	in the presence of:-  	 		 		 		 	
					
	Witness’ Name	 	  
	 		 	Address	 	  

					
	Witness’ Signature	 	  
	 		 		 	  

  

	*	Personal Representatives should enclose an Office Copy of the relevant Grant of Probate or Letters of Administration. 

	**	Persons exercising the option should consult with the Company as to whether any Tax Liability is anticipated, however the Company does not undertake to advise you on the tax consequences of exercising your Option. If
you are unsure of the tax liabilities which may arise you should take appropriate professional advice before exercising your Option. 

  
 24 

 SCHEDULE 3 

[Form EMI 1] 

  
 25 

 SCHEDULE 4 

S.431 ELECTION 
 Joint
Election under s431 ITEPA 2003 for full or partial disapplication of Chapter 2 
 Income Tax (Earnings and Pensions) Act 2003 

Employment-related securities acquired on exercise of qualifying options exercised before the tenth anniversary of the date of grant. 

One Part Election 
 Between 

 

					
	the Employee	  	      [●]	  	
			
	whose National Insurance Number is	  	      [●]	  	
			
	 and
  

the Company (which is the Employee’s employer)
	  	      [●] Limited	  	
			
	of Company Registration Number	  	      [●]	  	

 Purpose of Election 
 This
joint election is made pursuant to section 431(1) Income Tax (Earnings and Pensions) Act 2003 (ITEPA) and applies where employment-related securities, which are restricted securities by reason of section 423 ITEPA, are acquired. 

The effect of an election under section 431(1) is that, for the relevant Income Tax and NIC purposes, the employment-related securities and their market value
will be treated as if they were not restricted securities and that sections 425 to 430 ITEPA do not apply. 

 

Should the value of the securities fall following the acquisition, it is possible that Income Tax/NIC that
would have arisen because of any future chargeable event (in the absence of an election) would have been less than the Income Tax/NIC due by reason of this election. Should this be the case, there is no Income Tax/NIC relief available under Part 7
of ITEPA 2003; nor is it available if the securities acquired are subsequently transferred, forfeited or revert to the original owner. 

Application 
 This joint election is made not later than
14 days after the date of acquisition of the securities by the employee and applies to: 
  

			
	Number of securities	  	                                      
                      
		
	Description of securities	  	Ordinary shares in the capital of [●] Limited
		
	Name of issuer of securities	  	[●] Limited
		
	Acquired by the Employee on	  	                                      
                      

  
 26 

 Extent of Application 

This election disapplies S.431(1) ITEPA: All restrictions attaching to the securities. 

Declaration 
 This election will become irrevocable upon
the later of its signing or the acquisition of employment-related securities to which this election applies. 
 In signing this joint election, we agree to
be bound by its terms as stated above. 
  

							
	  
	  		  	         /         /            	  	
	Signature (Employee)	  		  	Date	  	
				
	  
	  		  	         /         /            	  	
	Signature (for and on behalf of the Company)	  		  	Date	  	
				
	  
	  		  		  	
	Position in company	  		  		  	

  
 27 

 OPTION AGREEMENT 
  

	
	THIS DOCUMENT IS IMPORTANT AND SHOULD BE KEPT IN A SAFE PLACE

 THIS OPTION AGREEMENT is made the [Date] day of [Month] 20     

BETWEEN 
  

	(1)	MIMECAST LIMITED (registered number 04698693) whose registered address is at 2-8 Balfe Street, London, N1 9EG; and 

  

	(2)	[Name] of [Address] (the “Option Holder”) 

 SUPPLEMENTAL to the rules of the
Mimecast Limited 2010 EMI Share Option Scheme (the “Scheme”). Any words or expressions used in this option agreement and defined by the Scheme shall bear the same meaning in this agreement. 

INTRODUCTION: 
  

	(A)	The Company intends to grant an Option to the Option Holder. 

  

	(B)	The Option is intended to be an EMI option. 

  

	(C)	The Option is granted under Schedule 5 ITEPA 2003. 

 AGREED TERMS 

 

	1.	Grant 

 The Company GRANTS an EMI option to the Option Holder and the Option
Holder AGREES to be bound in all respects by the provisions of the Scheme and ACCEPTS the grant on the terms set out in their agreement. 
  

	2.	Terms of the Scheme 

  

	2.1	Under the terms of the Scheme the Option Holder may acquire the number of ordinary shares (“Shares”) in the Company stated in clause 6(a) at the Option price per Share set out in clause 6.1. 

 

	2.2	The Option is granted and exercisable subject to the terms and conditions set out in the Scheme and in this Option Agreement. For the avoidance of any doubt, where the provisions of the Scheme and the Option Agreement
conflict, the Option Agreement shall take priority. 

  

	3.	Memorandum and articles 

 Any Shares allotted or transferred pursuant to the exercise of
the Option are subject to the memorandum and articles of association of the Company (as amended from time to time) and to any necessary consents of any governmental or other authorities under any enactments from time to time in force. 

	4.	Non transferable 

 The Option is personal to the Option Holder and is not transferable,
assignable or chargeable. 
  

	5.	Vesting and Exercise 

  

	5.1	The Option shall not be exercisable on or after the 10th Anniversary of the date of grant of the Original Option. 

 

	5.2	Rule 9.1(b) of the Scheme shall not apply to the Option, with the effect that the Option may be exercisable before an exit event, subject to satisfying the Vesting Schedule and the Exercise Condition. 

 

	6.	Grant 

  

	6.1	The details of the grant are as follows; namely 

  

							
	(a)	  	  Number of Shares subject to the Option	  	      [0,000].	  	
				
	(b)	  	  Option price per Share	  	      [£]	  	
				
	(c)	  	  Date of grant	  	      [Date]	  	
				
	(d)	  	  Vesting Commencement Date	  	      [Date]	  	

  

	6.2	The Option Holder irrevocably agrees to reimburse the Relevant Company for any Employer’s NICs arising on the exercise of an Option; or agrees to enter into an election with the Relevant Company to assume the
liability for any Employer’s NICs, payable on the exercise of the Option, including an election under paragraph 3B of Schedule 1 to the Social Security Contributions and Benefits Act 1992. 

 

	6.3	The exercise of the Option shall be conditional upon the Option Holder making good any Tax Liability in relation to the Option, or entering into arrangements acceptable to the Company in respect of such Tax Liability,
in accordance with rule 10.4 of the Scheme. 

  

	6.4	The exercise of the Option shall be subject to the following Exercise Conditions: 

 The Options
shall vest over a three year period from the Date of Grant subject to the performance condition outlined below. 
 The number of Shares that
shall Vest in each year is calculated as [4000] Shares multiplied by the percentage growth in Annual Recurring Revenue over the year. At the end of the three year period an additional amount of shares shall Vest calculated as the aggregate of the
growth in Annual Recurring Revenue over the three year period multiplied by [1,000] Shares. 
 Provided that at each point when determining
the number of Shares which Vest at the end of each year or the end of the three year period, the overall maximum number of Shares under Option shall not exceed the number of Shares set out in 6.1(a). 

 Vesting Schedule 

The Shares shall Vest and be exercisable over a three year period as outlined in 6.4 above. If any person obtains Control of
the Company as defined in Rule 12 of the scheme, then the proportion of Unvested Option that shall be regarded as Vested shall not be 75% as set out in Rule 12.1, but shall be equivalent to the average percentage growth in Annual Recurring Revenue
over period from the Date of Grant until the date of the change of Control. The figure of 25% in Rule 12.1 shall be changed accordingly. 
 This option
agreement has been executed as a deed and unconditionally delivered on the date first above written. 
  

					
	SIGNED as a DEED	  	)	  	
	By MIMECAST LIMITED acting by    	  	)	  	
			
		  		  	 Director

			
	Signature of Witness:	  		  	
			
	Name of Witness:	  		  	
			
	Address:	  		  	
			
	Occupation:	  		  	
			
	SIGNED as a DEED	  	)	  	
	By [Option Holder]	  	)	  	
			
	Signature of Witness:	  		  	
			
	Name of Witness:	  		  	
			
	Address:	  		  	
			
	Occupation:	  		  	

  

RULES OF 
 THE MIMECAST
LIMITED 2010 EMI SHARE OPTION SCHEME (FOR UNITED STATES EMPLOYEES) 
 (approved by the Board on March 23 2010) 

(amended by the Board on 13 May 2014) 

(amended by the Board on 28 April 2015) 
  

 
  
 

 
 Berlin, Brussels, Cambridge, Dubai, Düsseldorf, Frankfurt, Hamburg, London, Munich, Paris. 

Representative offices: Alicante, Beijing, Shanghai. Associated office: Warsaw 

 Index 
  

							
	Clause No.	  	Page No.	 
			
	 1.
	 	Interpretation and Construction	  	 	3	  
			
	 2.
	 	Statement of Purpose	  	 	7	  
			
	 3.
	 	Grant of Options	  	 	7	  
			
	 4.
	 	Notice of Grant	  	 	8	  
			
	 5.
	 	EMI Options: Limit for individual Eligible Employee	  	 	9	  
			
	 6.
	 	Overall limits for Company on the Grant of Options	  	 	9	  
			
	 7.
	 	Ordinary Share Capital	  	 	9	  
			
	 8.
	 	Non-Transferable	  	 	9	  
			
	 9.
	 	Rights to Exercise Options	  	 	10	  
			
	 10.
	 	Exercise of Options	  	 	11	  
			
	 11.
	 	Lapse of Options	  	 	13	  
			
	 12.
	 	Takeover, Reconstruction, Liquidation and Sale of the Business	  	 	13	  
			
	 13.
	 	Replacement Options	  	 	15	  
			
	 14.
	 	Loss of Office or Employment	  	 	17	  
			
	 15.
	 	Adjustments	  	 	18	  
			
	 16.
	 	General	  	 	18	  
			
	 17.
	 	Overseas Employees	  	 	20	  
			
	 18.
	 	Supplementary Provisions	  	 	20	  
		
	 SCHEDULE 1
	  	 	21	  
		
	 SCHEDULE 2
	  	 	25	  

  
 2 

	1.	Interpretation and Construction 

  

	1.1	Definitions 

 In the Rules, unless the context requires otherwise, the following words
and expressions are defined or otherwise explained by the provisions indicated: 
  

	 “Acquiring Company” 
	any company which has obtained Control of the Company in accordance with any of the provisions of Rule 12; 

  

	 “Adoption Date” 
	the date on which the Rules are adopted by the Directors; 

  

	 “Bad Leaver” 
	any director or employee of any Group Company who ceases to be a director or employee without becoming a director or employee of any other Group Company and is not a Good Leaver; 

 

	 “Committed Time” 
	the meaning given by paragraph 26 of Schedule 5; 

  

	 “Companies Act” 
	the Companies Act 2006; 

  

	 “Company” 
	Mimecast Limited (registered number 04698693) whose registered address is at 2-8 Balfe Street, London, N1 9EG; 

  

	 “Control” 
	the meaning given by section 995 of the Tax Act; 

  

	 “Date of Grant” 
	the date on which an Option is granted to an Employee; 

  

	 “Directors” 
	the board of Directors of the Company or a duly authorised committee thereof; 

  

	 “Disqualifying Event” 
	the meaning given by Sections 534 to 536 of ITEPA; 

  

	 “Eligible Employee” 
	any person who is an employee of the Company or any Qualifying Subsidiary PROVIDED THAT where an Option is intended to be an EMI Option the Employee is an individual; 

 

	 	(a)	whose Committed Time amounts to at least 25 hours a week, or if less, 75% of his Working Time; and 

  

	 	(b)	who does not have a Material Interest in any Group Company; 

  

	 “EMI” 
	Enterprise Management Incentive; 

  

	 “EMI Option” 
	any right to acquire Shares: 

  

	 	(a)	in relation to which the requirements of Schedule 5 are met at the Date of Grant; and 

  
 3 

	 	(b)	of which Notice of Grant is given to HM Revenue & Customs in accordance with paragraph 44 of Schedule 5; 

  

	 	and, where the circumstances permit, a Replacement Option in relation to that EMI Option; 

  

	 “Employee” 
	any individual who is an employee of a Group Company; 

  

	 “Employer Company” 
	the company by reference to which the Option Holder is an Eligible Employee or Employee; 

  

	 “Employer’s NICs” 
	secondary Class 1 national insurance contributions; 

  

	 “Exercise Conditions” 
	any performance conditions set by the Directors under rule 3.4; 

  

	 “Exercise Period” 
	the period during which an Option may be exercised, which in any event shall terminate no later than the day before the 10th anniversary of the Date of Grant; 

 

	 “Good Leaver” 
	any director or any employee of any Group Company who ceases to be a director or employee without becoming a director or employee of any other Group Company by reason of injury or disability or in any other circumstance where the Directors, in
their absolute discretion, determine the director or employee to be a Good Leaver; 

  

	 “Group” and “Group Company” 
	“group”, in relation to a Parent Company, means that company and its Subsidiaries and “Group Company” shall be construed accordingly; 

  

	 “Independence Requirement” 
	the meaning given by paragraph 9 of Schedule 5; 

  

	 “ITEPA” 
	the Income Tax (Earnings and Pensions) Act 2003; 

  

	 “Market Value” 
	shall be determined in accordance with Part VIII of the Taxation of Chargeable Gains Act 1992; 

  

	 “Material Interest” 
	the meaning given by paragraph 29 of Schedule 5; 

  

	 “Notice of Exercise” 
	a notice of exercise in accordance with the form set out in Schedule 2 of the Rules or such other form as may be prescribed or required by the Directors from time to time; 

 

	 “Notice of Grant” 
	the notice of grant of the EMI Option issued by the Employer Company to HM Revenue & Customs in accordance with Rule 4.1; 

  

	 “Option” 
	a right to acquire Shares which shall include an EMI Option or an Unapproved Option; 

  
 4 

	 “Option Agreement” 
	an agreement between the Company and an Eligible Employee (or the Company and an Employee) which shall evidence the grant of the Option, which shall be in accordance with the Rules of the Scheme and which shall be in such form as may be
prescribed by the Directors; 

  

	 “Option Holder” 
	an Eligible Employee who has been granted an EMI Option or an Employee who has been granted an Unapproved Option (or his legal personal representatives where the circumstances permit); 

 

	 “Option Price” 
	the price per Share determined by the Directors which shall not be less than the Market Value of a Share on the Date of Grant and, in the case of an Option which is a right to subscribe for Shares, not less than the nominal value of a Share;

  

	 “Ordinary Share Capital” 
	the meaning given by section 989 of the Tax Act; 

  

	 “Parent Company” 
	a company that has one or more Subsidiaries; 

  

	 “Personal Representatives” 
	in relation to an Option Holder, the Option Holder’s legal personal representatives (being either the executors of his will to whom a valid grant of probate has been made or the duly appointed administrators of his estate) who in either
case have provided the Directors with satisfactory evidence of their appointment; 

  

	 “Qualifying Exchange” 
	an exchange of Shares in accordance with Rule 13.3; 

  

	 “Qualifying Subsidiary”  
	the meaning given by paragraph 11 of Schedule 5 to ITEPA; 

  

	 “Relevant Company” 
	the company (being either the Company or any Group Company) which incurs a Tax Liability as set out in Rule 10.4; 

  

	 “Replacement Option” 
	an Option granted in accordance with Rule 13; 

  

	 “Restrictions” 
	any condition attaching to the Shares which makes the interest in the Shares restricted within the meaning of Chapter 2 of Part VII of ITEPA; 

  

	 “Rules” 
	these rules together with any schedules or appendices to these rules; 

  

	 “Sale of the Business” 
	any transfer (whether through a single transaction or a series of transactions) of all or substantially all of the assets or undertaking of the Group (including goodwill) to any person (or persons connected with each other or act in concert with
each other); 

  

	 “Scheme” 
	this scheme as governed by the Rules; 

  

	 “Scheme of Reconstruction” 
	the meaning given by Rule 12.3; 

  
 5 

	 “Section 431 Election” 
	means an election in accordance with Section 431 of ITEPA being in the form as set out in Schedule 4 to this Scheme or in such other form as HM Revenue & Customs may determine from time to time; 

 

	 “Share” 
	Ordinary Shares in the capital of the Company (and in the context of an EMI Option, which satisfies the requirements of paragraph 35 of Schedule 5); 

  

	 “Schedule 5” 
	Schedule 5 to ITEPA; 

  

	 “Subsidiary”  
	means any body corporate which is a subsidiary of the Company within the meaning of section 1159 of the Companies Act 2006. 

  

	 “Tax Liability” 
	a liability to account for any employee’s tax, national insurance, social security or other levies in respect of the Option (including Employer’s NICs or equivalent employer’s social security contributions) (whether by reason of
grant, exercise, or otherwise or by reason of a Disqualifying Event in relation to EMI Options only), including for the avoidance of doubt and without limitation any liability arising after the termination of the Option Holder’s employment for
whatever reason and which: 

  

	 	(a)	may arise or be incurred in any jurisdiction whatsoever and, 

  

	 	(b)	by the law of the same jurisdiction may or shall be recovered from the person entitled to the Option; 

  

	 “Tax Act” 
	the Income Tax Act 2007; 

  

	 “Trading Activities Requirement” 
	the meaning given by paragraph 13 to 14 of Schedule 5; 

  

	 “Unapproved Options” 
	any right to acquire Shares granted pursuant to this Scheme which does not satisfy the requirements of Schedule 5; 

  

	 “Unvested” 
	such number or the proportion of the Shares subject to an Option that are not Vested; 

  

	 “Vested” 
	such number or the proportion of the Shares subject to an Option that shall become vested according to the Vesting Schedule and “Vest” shall be construed accordingly; 

 

	 “Vesting Schedule” 
	unless otherwise specified in the schedule in the Option Holder’s Option Agreement the Vesting Schedule shall be as follows: 

  

	 	 25% of the Options shall be vested on the first anniversary of the Date of Grant and thereafter 6.25% of the Options shall vest at the expiry of 3 months from

  
 6 

	 	 
such anniversary and at the expiry of every subsequent 3 months period until the Options are fully vested on the fourth anniversary of the Date of Grant. 

 

	 “Working Time” 
	the meaning given by paragraph 27 of Schedule 5; 

  

	 “Year” 
	a financial year of the Company. 

  

	1.2	Construction 

 Words or expressions used herein shall where appropriate: 

 

	 	(a)	when denoting the masculine gender include the feminine and vice-versa; 

  

	 	(b)	when denoting the singular include the plural and vice versa; 

  

	 	(c)	when referring to any enactment be construed as a reference to that enactment as for the time being consolidated, amended, re-enacted or replaced and shall include any regulations made thereunder; 

 

	 	(d)	when a period of time is specified and starts from a given day or the day of an act or event, be calculated exclusive of that day; and 

 

	 	(e)	be construed such that the headings and sub-headings are for ease of reference only, and do not affect the interpretation of any Rule; 

 

	 	(f)	be construed where not otherwise defined in the Rules to have the same meanings as in Schedule 5. 

  

	2.	Statement of Purpose 

 EMI Options granted at any time pursuant to the Rules are granted
for commercial reasons in order to recruit or retain an Eligible Employee and not as part of a scheme or arrangement the main purpose, or one of the main purposes, of which is the avoidance of tax. 

 

	3.	Grant of Options 

  

	3.1	General 

  

	 	(a)	Subject to the Rules, the Company may, at any time, grant 

  

	 	(i)	any Eligible Employee an EMI Option; or 

  

	 	(ii)	any Employee an Unapproved Option 

 over such number of Shares at such Option Price and with
such conditions of exercise as the Company may determine. 
  

	 	(b)	An EMI Option shall be granted in accordance with the provisions of Schedule 5. 

  

	 	(c)	EMI Options shall only be granted to individuals who are Eligible Employees. 

  
 7 

	 	(d)	Unapproved Options shall only be granted to individuals who are Employees. 

  

	 	(e)	An Option shall not be granted by any person other than the Company without the prior approval of the Directors. 

  

	3.2	Contents of Option Agreement 

 The Option shall be agreed in writing between the Company
and the Option Holder, and shall state: 
  

	 	(a)	the Date of Grant; 

  

	 	(b)	that the EMI Option is granted under the provisions of Schedule 5; 

  

	 	(c)	the number or maximum number of Shares over which the Option is granted; 

  

	 	(d)	the Option Price, or the method by which the Option Price is to be determined; 

  

	 	(e)	the Vesting Schedule; 

  

	 	(f)	the Exercise Period and; 

  

	 	(g)	details of any Restrictions attaching to the Shares and, if so, shall contain details of such Restrictions. 

  

	3.3	The Option Agreement for an Unapproved Option shall be in the same form as Rule 3.2 apart from Rule 3.2(b) and (g) which shall not apply. 

 

	3.4	The Directors may at the Date of Grant impose such performance condition or performance conditions to be satisfied upon the exercise of an Option. Such performance conditions: 

 

	 	(a)	must be objective and stated in writing at the Date of Grant; 

  

	 	(b)	may not be waived, varied or amended by the Directors unless in accordance with the terms of such conditions or, where any waiver, variation or amendment is at the discretion of the Directors, it shall only be exercised
in a manner which the Directors have determined to be fair and reasonable and, if events happen which cause the Directors, acting fairly and reasonably, to consider that the waived, varied or amended condition would be appropriate and would result
in the waived, varied or amended condition being no easier and no more difficult to satisfy than the condition as it existed immediately prior to such waiver, variation or amendment. 

 

	4.	Notice of Grant 

  

	4.1	On the grant of an EMI Option, a Notice of Grant shall be given by the Employer Company to HM Revenue & Customs within 92 days of the Date of Grant (or such further or other period as HM Revenue &
Customs or statute may allow, permit or require) and shall: 

  

	 	(a)	be in the form set out in Schedule 3 of the Rules or in such form as required by HM Revenue & Customs from time to time; 

  

	 	(b)	contain a declaration by the Option Holder that he satisfies the Working Time requirement; 

  
 8 

	 	(c)	contain a declaration by a director or the secretary of the Employer Company that: 

  

	 	(i)	in his opinion the requirements of Schedule 5 are met; and 

  

	 	(ii)	the information provided is to the best of his knowledge correct and complete. 

  

	4.2	On the grant of an Unapproved Option a Notice of Grant shall not be required. 

  

	5.	EMI Options: Limit for individual Eligible Employee 

  

	5.1	The number of Shares over which an EMI Option may be granted to any one Eligible Employee shall be limited and take effect so that the total value of Shares (as determined by paragraphs 5(6) to (8) of Schedule 5)
subject to unexercised EMI Options granted to that Eligible Employee by the Company or any other Group Company does not exceed £1 less than £120,000 (or such other limit as may apply from time to time in paragraph 5 of Schedule 5), SAVE
WHERE an EMI Option is granted under the provisions of Part 6 (Company Reorganisation) of Schedule 5. 

  

	5.2	Provided that if an EMI Option exceeds the limit in Rule 5.1 the Option shall be treated as two Options, one shall be an EMI Option as to the number of Shares to the value of £1 less than the limit in Rule 5.1 and
the other Option relating to the excess shall be an Unapproved Option. 

  

	6.	Overall limits for Company on the Grant of Options 

  

	6.1	Subject to such adjustments as may be made in accordance with Rule 15, no Option shall be granted on any Date of Grant if as a result the total value of Shares of the Company (as determined by paragraphs 5(6) to
(8) of Schedule 5) in respect of which unexercised EMI Options exist would exceed £3 million or such other limit as may apply from time to time in paragraph 7 of Schedule 5. 

 

	6.2	For the purpose of the limit contained in Rule 6.1 above, any Option or right which has been released, cancelled or lapsed without being exercised shall be ignored. 

 

	6.3	If following the purported grant of an EMI Option the limit in Rule 6.1 would be exceeded such an Option shall not be an EMI Option insofar as it relates to the excess. 

 

	7.	Ordinary Share Capital 

  

	7.1	Availability of authorised capital and Shares 

 The Company shall at all times keep
available sufficient authorised and unissued Shares to satisfy the exercise to the full extent still possible of all Options which have neither lapsed nor been fully exercised taking account of any other obligations of the Company to provide shares
of the same class as Shares. 
  

	8.	Non-Transferable 

 Save as provided in Rule 9.4, no Option nor any right thereunder shall
be capable of being transferred, assigned or charged in any manner whatsoever. Upon any such purported transfer, assignment, or charge the Option shall immediately lapse and cease to be exercisable. 

  
 9 

	9.	Rights to Exercise Options 

  

	9.1	General 

 Subject to rules 9.2, 9.3, 9.4, 9.5 and 12 below an Option: 

 

	 	(a)	shall not be exercisable before it has Vested in accordance with the Vesting Schedule; and 

  

	 	(b)	shall not be exercisable until an exit event set out in rule 12, subject to the provisions of the Option Agreement and subject to the provisions in rule 12.3; 

 

	 	(c)	shall not be exercisable unless the Exercise Conditions (if any) (as waived, varied or amended) have been fulfilled to the satisfaction of the Directors; and 

 

	 	(d)	shall not be exercised later than the day before the tenth anniversary of the Date of Grant. 

  

	9.2	Termination of Employment 

 If the Option Holder is a Bad Leaver, the Option, whether
Vested and unexercised or Unvested shall lapse immediately on the date upon which the Option Holder ceases to hold employment or office within the Group, or in the case of gross misconduct, on the date of occurrence of such misconduct. 

 

	9.3	Good Leaver 

 If the Option Holder is a Good Leaver: 

 

	 	(a)	the Option shall be exercisable to the extent Vested as at the date of ceasing employment within 39 days of ceasing employment (provided that the Directors shall have the discretion to waive the Exercise Conditions (if
any) relating to such Option); 

  

	 	(b)	the Option to the extent Unvested shall lapse immediately on the date upon which the Option Holder ceases employment, unless the Directors in their discretion determine before cessation that the Unvested Option may be
exercised within 39 days of ceasing employment. 

  

	9.4	Death of the Option Holder 

 If an Option Holder dies, the Option shall be exercisable to
the extent Vested as at the date of the Option Holder’s death by the Personal Representatives, provided that the Option shall only be exercisable within 12 months of the Option Holder’s death (and provided that the Directors shall have the
discretion to waive the Exercise Conditions (if any) relating to such Option). To the extent that the Option is Unvested the Option shall lapse on the date of the Option Holder’s death. 

  
 10 

	9.5	Admission to Main Market of London Stock Exchange, AIM or other securities exchange – for Options granted before 13 May 2014 only 

If the Company’s shares are admitted to listing on the Main Market of the London Stock Exchange, AIM, or other securities exchange, the
Option shall Vest in full immediately after the admission date (notwithstanding that part of the Option may be Unvested). The Option will be exercisable (subject to the discretion of the Board to permit an earlier exercise) as follows: 

 

	 	(a)	25% immediately following the admission date; 

  

	 	(b)	a further 50% on the first anniversary of the admission date; 

  

	 	(c)	a further 25% on the second anniversary of the admission date. 

  

	9.6	Admission to Main Market of London Stock Exchange, AIM or other securities exchange – for Options granted on or after 13 May 2014 

For the avoidance of doubt, Rule 9.5 shall not apply to all Options granted on or after 13 May 2014 and on admission vesting shall
continue as detailed in the Vesting Schedule. 
  

	10.	Exercise of Options 

  

	10.1	Procedure on exercise 

 An Option shall be exercisable, in whole or in part, by the
delivery to the secretary of the Company of the following: 
  

	 	(a)	an Option Agreement covering all of the Shares over which the Option is then to be exercised; 

  

	 	(b)	the Notice of Exercise in the prescribed form duly completed and signed by the Option Holder (or by his duly authorised agent); 

  

	 	(c)	a Section 431 Election (or a similar election should the Directors so require); 

  

	 	(d)	payment (in such manner as the Directors shall permit) of a sum equal to the aggregate Option Price for the number of Shares over which the Option is to be exercised; 

 

	 	(e)	payment (in such manner as the Directors shall permit) of any Tax Liability including Employer’s NICs in accordance with Rule 10.4; and 

 

	 	(f)	if there is a shareholders’ agreement or other such document (which contains restrictions on the Shares), is accompanied by a deed of adherence, in a form acceptable to the Company and executed by the Option
Holder, whereby the Option Holder agrees to be bound by the terms of such shareholders’ agreement or other such document. 

  

	10.2	Issue or transfer of Shares 

 The Company shall issue or procure the transfer of Shares
to be allotted or transferred pursuant to the exercise of an Option to the Option Holder such number of Shares within 30 days following the effective date of exercise of the Option. 

  
 11 

	10.3	Shares issued pursuant to the Scheme will rank pari passu in all respects with the Shares then already in issue except that they and any Shares transferred pursuant to the Scheme will not rank for any dividend or other
distribution of the Company paid or made by reference to a record date falling prior to the date of receipt of the Notice of Exercise of the Option pursuant to Rule 10.1. 

 

	10.4	Deductions 

  

	 	(a)	Where in relation to Options, the Company or any Group Company (“the Relevant Company”) is liable, or is in accordance with current practice believed to be liable under any statute or regulation or otherwise,
to account to any revenue or other authority for sums in respect of a Tax Liability in relation to the Option, the Option Holder shall indemnify and shall keep indemnified the Relevant Company for the Tax Liability and the Option Holder shall pay
the Relevant Company a sum equal to the Tax Liability immediately upon written notice of the quantum of the said liability. 

  

	 	(b)	Notwithstanding the above, the Company may impose such conditions upon the exercise of the Options as are necessary to ensure that the Relevant Company is able to meet any or all of such liabilities, including, without
limitation, a condition that no exercise may take place unless the Option Holder has provided the Relevant Company with cash funds sufficient to meet such Tax Liability, or has entered into arrangements acceptable to the Relevant Company to secure
that such cash funds are available, or to allow the Relevant Company to deduct the amount of such Tax Liability from any cash amounts (including salary and bonuses) which may become payable to the Option Holder by any Group Company.

  

	 	(c)	The Company may require the Option Holder as a condition of the exercise of any Option that the Option Holder shall: 

  

	 	(i)	agree to reimburse the Relevant Company for any Employer’s NICs arising on the exercise of an Option; or 

  

	 	(ii)	enter into an election with the Relevant Company to assume the liability for any Employer’s NICs, payable on the exercise of the Option, including an election under paragraph 3B of Schedule 1 to the Social Security
Contributions and Benefits Act 1992; OR 

  

	 	(iii)	agree to pay the employer’s social security contributions, to the extent permitted by law, in any other jurisdiction. 

  

	 	(d)	If the Option Holder shall fail to: 

  

	 	(i)	make payment to the Relevant Company immediately upon receipt of a written notice in accordance with Rule 10.4(a); or 

  

	 	(ii)	reimburse the Relevant Company in accordance with an agreement or election in whole or in part for any liability to employer’s secondary national insurance contributions or employer’s social security
contributions pursuant to Rule 10.4(c); 

 then the Company shall be authorised by the Option Holder to reduce the number of
Shares otherwise deliverable to the Option Holder upon the exercise of an Option as may be sufficient to produce a sum which (after allowance for the costs and expenses of such a sale) may discharge (and shall be applied in discharge of) the Option
Holder’s liability to the Relevant Company under Rule 10.4(a) or any agreement or election pursuant to Rule 

  
 12 

 
10.4(c) and the Company may exercise all such powers and may appoint any of its officers to sign all such documents in the name of the Option Holder and as his act and deed as may be necessary
for this purpose. 
  

	 	(e)	If the Option Holder shall fail to make payment to the Relevant Company immediately upon receipt of a written notice in accordance with Rule 10.4(a) then the Option Holder shall be liable to make good any amount
outstanding on demand. 

  

	11.	Lapse of Options 

  

	11.1	General 

 An Option shall immediately cease to be exercisable and shall lapse on the
earliest of: 
  

	 	(a)	the tenth anniversary of the Date of Grant; 

  

	 	(b)	the date upon which the Option Holder ceases to hold employment or office within the Group if the Option Holder is a Bad Leaver; 

  

	 	(c)	the expiry of the period in Rule 9.3, except that if the Option Holder dies during the exercise period specified in Rule 9.3, an Option shall not lapse by reason of this Rule 11.1 (c) until the first anniversary of
the Option Holder’s death, if later; 

  

	 	(d)	the first anniversary of the Option Holder’s death; 

  

	 	(e)	subject to Rule 13.1, the expiry of any of the periods referred to in Rule 12; 

  

	 	(f)	the date on which it is purported to be transferred or assigned (other than by reason of death in accordance with Rule 9.4), mortgaged, charged or otherwise disposed of by the Option Holder; 

 

	 	(g)	the presentation of any petition to any court of competent jurisdiction by which an order is sought for the bankruptcy of the Option Holder; 

 

	 	(h)	upon the Option Holder making an application for an interim order or any proposal for a voluntary arrangement within Part VIII of the Insolvency Act 1986; 

 

	 	(i)	upon the Option Holder proposing any form of compromise with his creditors or any class of creditors; and 

  

	 	(j)	the date on which the Option Holder is deprived (otherwise than on death) of the legal or beneficial ownership of the Option by operation of law or by the Option Holder doing or omitting to do anything which causes him
to be so deprived. 

  

	12.	Takeover, Reconstruction, Liquidation and Sale of the Business 

  

	12.1	General Offer 

 If any person obtains Control of the Company as a result of: 

 

	 	(a)	making an offer to acquire the whole of the issued share capital of the Company which is made on a condition such that, if it is satisfied, the person making the offer will have Control of the Company; or

  
 13 

	 	(b)	negotiating a share sale and purchase agreement with the shareholders of the Company which contemplates that the person will obtain Control of the Company on completion; 

(“a General Offer”), an Option may be exercised in accordance with the provisions in rule 12.3, to the extent Vested and to the
extent that the Exercise Conditions (if any) have been satisfied (and 75% of the Unvested Option shall be regarded as Vested and the remaining 25% of the Unvested Option may only be exercisable if the Directors determine that the circumstances
justify the exercise of a larger proportion than 75% of the Unvested Option). 
  

	12.2	Control 

 For the purposes of Rule 12.1 a person shall be deemed to have obtained Control
of the Company if he and others acting in concert with him have together obtained Control of it. 
  

	12.3	Exercise period for options and the offer of Replacement Options on a takeover 

  

	 	(a)	If Replacement Options are offered to all Option Holders by the Acquiring Company in relation to the Vested Options (including the Options which have been Vested due to the Change of Control) and an Option Holder does
not agree to release the Vested Options and accept the Replacement Option, the Board shall determine whether such Vested Options shall be exercisable in accordance with rule 12.3 (d) below or whether such Vested Options shall lapse.

  

	 	(b)	If Replacement Options are offered to all Option Holders by the Acquiring Company in relation to the Vested Options (including the Options which have been Vested due to the Change of Control) and an Option Holder does
agree to release the Vested Options and accept the Replacement Option, the terms of rule 13 shall apply to the Replacement Option. 

  

	 	(c)	If Replacement Options are not offered to all Option Holders then the Vested Options shall be exercisable in accordance with rule 12.3 (d) below. 

 

	 	(d)	In the circumstances set out in this rule 12.3, the Vested Options can be exercised in either of the following exercise periods determined by the Directors: - 

 

	 	(i)	Immediately before the change of Control becoming unconditional; or 

  

	 	(ii)	During a one month exercise period starting at a date to be determined by the Directors but such period to take place before the expiry of the 12 months period commencing on the change of Control becoming unconditional.

  

	12.4	Scheme of Reconstruction 

 If any person obtains Control of the Company in pursuance of a
compromise or arrangement sanctioned by the court under section 900 of the Companies Act or Article 418 of the Companies (Northern Ireland) Order 1986 (“a Scheme of Reconstruction”), an Option may be exercised to the extent Vested (and may
only be exercised to the extent Unvested if the Board in its discretion permits exercise) within 39 days of the court sanctioning the Scheme of Reconstruction. An Option shall not be exercisable after the said 39 days but may still be released under
Rule 13 within the period of six months following the court sanction of the Scheme of Reconstruction and, on the expiry of the said six month period, the Option shall lapse. 

  
 14 

	12.5	Chapter 3, Part 28 of the Companies Act 

 If any person becomes bound or entitled to
acquire shares under Chapter 3, Part 28 of the Companies Act, an Option may be exercised to the extent Vested (and may only be exercised to the extent Unvested if the Board in its discretion permits exercise) at any time when that person remains so
bound or entitled. 
  

	12.6	Liquidation 

 If a general meeting of the Company is called at which it is proposed to
pass a resolution for the voluntary winding up of the Company, the Company shall notify the Option Holder as soon as practicable of this fact. The Option may be exercised to the extent Vested (and may only be exercised to the extent Unvested if the
Board in its discretion permits exercise) during the period of such notice (such exercise being conditional on such resolution being passed and taking effect immediately thereafter) and such portion of the Option not otherwise exercised before such
resolution has been passed shall thereupon lapse. Where the Option Holder has exercised the Option pursuant to this Rule 12.6 and the resolution referred to above has been passed then (subject to the consent of the Company’s liquidator where
such is required by section 88 of the Insolvency Act 1986) the exercise of the Option shall take effect immediately and the Option Holder shall be entitled to share in the assets of the Company with the existing shareholders in the same manner as
the Option Holder would have been entitled had the Option Holder been the registered owner of the relevant Shares before the resolution was passed. 
  

	12.7	Reorganisation 

 An option may not be exercised under rule 12.1 if the General Offer is
part of a reorganisation so that the shareholders of the Acquiring Company hold their shares in the Acquiring Company in the same proportions as they held their shares in the Company. 

 

	12.8	Sale of Business 

 An Option may be exercised to the extent Vested (and may only be
exercised to the extent Unvested if the Board in its discretion permits exercise) within 39 days of a Sale of the Business and the Company shall notify the Option Holder as soon as practicable of this fact. 

 

	13.	Replacement Options 

  

	13.1	Grant of Replacement Options 

 If any company (“the Acquiring Company”): 

 

	 	(a)	obtains Control of the Company as a result of making a General Offer in accordance with Rule 12.1; or 

  

	 	(b)	obtains Control of the Company as a result of a Scheme of Reconstruction in accordance with Rule 12.3; or 

  

	 	(c)	becomes bound or entitled to acquire the Shares under Chapter 3, Part 28 of the Companies Act in accordance with Rule 12.4, or 

  
 15 

	 	(d)	obtains all the Shares as a result of a Qualifying Exchange within Rule 13.3, 

 an Option Holder
may at any time within the period set out in Rule 13.2, by agreement with the Acquiring Company, release any Option which has not lapsed (“the Old Option”) in consideration of the grant to him of an Option (“the New Option”)
which is equivalent to the Old Option but relates to shares in the Acquiring Company and qualifies as a Replacement Option as set out in rules 13.4 and 13.5. 
  

	13.2	Period within which Replacement Option to be granted 

 The New Option must be granted
within the following periods: 
  

	 	(a)	if the change of Control is by reason of a general offer in accordance with Rule 12.1, the period of six months beginning with the time when the person making the offer has obtained control of the Company and any
condition subject to which the offer is made is satisfied; 

  

	 	(b)	if the change of Control is by reason of a Scheme of Reconstruction (in accordance with Rule 12.3) or a Qualifying Exchange the period of six months beginning with the time when the Acquiring Company obtains Control of
the Company whose shares are subject to the Old Option; 

  

	 	(c)	if the change of Control occurs under Chapter 3, Part 28 of the Companies Act, the period during which the Acquiring Company remains bound or entitled in accordance with those procedures. 

 

	13.3	Exchange of Shares 

  

	 	(a)	An exchange of shares will be treated as a Qualifying Exchange where arrangements are made in accordance with which a company (“the New Company”) acquires all the shares (“Old Shares”) in another
company (“the Old Company”) and the following conditions are met: 

  

	 	(i)	that the consideration for the Old Shares consists wholly of the issue of shares (“New Shares”) in the New Company; 

  

	 	(ii)	that New Shares are issued in consideration of Old Shares only at times when there are no issued shares in the New Company other than: 

 

	 	(A)	subscriber shares, and 

  

	 	(B)	New Shares previously issued in consideration of Old Shares; 

  

	 	(iii)	that the consideration for New Shares of each description consists wholly of Old Shares of the corresponding description; 

  

	 	(iv)	that New Shares of each description are issued to the holders of Old Shares of the corresponding description in respect of, and in proportion to, their holdings; and 

 

	 	(v)	that by virtue of section 127 of the Taxation of Chargeable Gains Act 1992 as applied by section 135(3) of that Act, the exchange of shares is not treated as involving a disposal of the Old Shares or an acquisition of
the New Shares. 

  

	 	(b)	 For the purposes of this rule Old Shares and New Shares are of a corresponding description if, on the assumption that they were shares in the

  
 16 

	 	
same company, they would be of the same class and carry the same rights, and references to “shares”, except in the expression “subscriber shares”, includes securities.

  

	13.4	Qualifying requirements for Replacement Option 

 Subject to Rule 13.5, a New Option
qualifies as a Replacement Option only if: 
  

	 	(a)	the New Option is granted to the Option Holder by reason of his employment: 

  

	 	(i)	with the Acquiring Company, or 

  

	 	(ii)	if that company is a Parent Company, with that company or another Group Company; 

  

	 	(b)	at the time of the release of rights under the Old Option, the purpose for granting the New Option is for commercial reasons in order to recruit or retain an Eligible Employee, and not as part of a scheme or arrangement
the main purpose, or one of the main purposes, of which is the avoidance of tax; 

  

	 	(c)	at that time, 

  

	 	(i)	the Independence Requirement and the Trading Activities Requirement are met in relation to the Acquiring Company; 

  

	 	(ii)	the individual to whom the New Option is granted is an Eligible Employee in relation to the Acquiring Company; and 

  

	 	(iii)	the New Option would satisfy the requirements of being an EMI Option set out in Part V of Schedule 5; 

  

	 	(d)	the total Market Value, immediately before the release, of the Shares which were subject to the Old Option is equal to the total Market Value, immediately after the grant, of the Shares in respect of which the New
Option is granted; and 

  

	 	(e)	the total amount payable by the employee for the acquisition of shares in pursuance of the New Option is equal to the total amount that would have been payable for the acquisition of shares in pursuance of the Old
Option. 

  

	13.5	Provided that a Replacement Option for an Unapproved Option shall not have to satisfy the requirements in Rule 13.4(b) and Rule 13.4(c). 

 

	13.6	Where, in accordance with this Rule 13, an Option is released and a New Option granted, the New Option shall not be exercisable in accordance with Rule 12 by virtue of the event which gave rise to the New Option being
granted. 

  

	14.	Loss of Office or Employment 

  

	14.1	The grant of an Option does not form part of the Option Holder’s entitlement to remuneration or benefits pursuant to his contract of employment nor does the existence of a contract of employment between an Eligible
Employee and any company give such Eligible Employee any right or entitlement to have an Option granted to him in respect of any number of Shares or any expectation that an Option might be granted to him whether subject to any conditions or at all
and the grant of an Option shall not give him any entitlement or expectation that further Options will be granted. 

  
 17 

	14.2	The rights and obligations of an Option Holder under the terms and conditions of his office or employment shall not be affected by his participation under the Rules or any right he may have to participate.

  

	14.3	An individual who participates under the Rules waives all and any rights to compensation or damages in consequence of the termination of his office or employment with any company for any reason whatsoever, whether
lawful or not, in so far as those rights arise, or may arise, from his ceasing to have rights under or be entitled to exercise any Option under the Rules as a result of such termination or from the loss or diminution of value of such rights or
entitlements. If necessary, the Option Holder’s terms of employment shall be varied accordingly. 

  

	15.	Adjustments 

  

	15.1	General rule 

 The number of Shares over which an Option is granted and the Option Price
thereof shall be adjusted in such manner as the Directors shall determine following any capitalisation issue, rights issue, subdivision, consolidation or reduction of share capital of the Company or any other variation of share capital to the intent
that (as nearly as may be) the total Option Price multiplied by the number of Shares that is payable in respect of an Option shall remain unchanged. 
  

	15.2	Reduction of Option Price to below nominal value 

 Subject to Rule 15.3 below, an
adjustment may be made under Rule 15.1 above which would have the effect of reducing the Option Price of unissued shares to less than the nominal value of a Share, but only if, and to the extent that, the Directors shall be authorised to capitalise
from the reserves of the Company a sum equal to the amount by which the aggregate nominal value of the Shares in respect of which the Option is exercisable exceeds the aggregate adjusted Option Price, so that on exercise of any Option in respect of
which the Option Price has been reduced, the Directors shall capitalise and apply such sum (if any) as is necessary to pay up the amount by which the aggregate nominal value of the Shares in respect of which the Option is exercised exceeds the
aggregate Option Price for such Shares. 
  

	15.3	Option over issued and unissued Shares 

 Where an Option subsists over both issued and
unissued Shares, an adjustment permitted by Rule 15.2 above, may only be made if the reduction of the Option Price of both issued and unissued Shares can be made to the same extent. 

 

	15.4	Administrative steps 

 The Directors shall notify Option Holders of any adjustment made
under this Rule 15 as soon as reasonably practicable and may take such steps and the Company shall execute such documents as it considers necessary to give effect to such adjustment. Furthermore, and without limitation to the generality of the
foregoing, the Directors may call in, cancel, endorse, issue or reissue any Option Agreement subsequent upon such adjustment. 
  

	16.	General 

  

	16.1	Amendments 

  

	 	(a)	Subject to rules 16.1(b) to (d), the Directors shall have the discretion to: 

  
 18 

	 	(i)	amend or add to the Rules; and 

  

	 	(ii)	impose additional conditions or requirements on the Options or on the terms on which Shares are acquired. 

  

	 	(b)	No amendments may be made to the Rules which would have the effect of causing EMI Options to cease to be EMI Options. 

  

	 	(c)	The Directors may at any time make such alterations (including additions) to the Rules as are necessary to secure that the Rules as applicable to EMI Options are in accordance with Schedule 5 and continue to be in
accordance with Schedule 5. 

  

	 	(d)	No amendment or addition shall be made to the Rules which would abrogate or adversely affect the subsisting rights of Option Holders unless: 

 

	 	(i)	where the rights are enjoyed by a single Option Holder and are not enjoyed by any other Option Holder or class of Option Holders, it is made with the written consent of that Option Holder; or 

 

	 	(ii)	where the rights are enjoyed by all Option Holders or any class of Option Holders then: 

  

	 	(A)	with the consent in writing of such number of Option Holders or class of Option Holders (as the case may be) as hold Options under the Scheme to acquire 75 per cent (75%) of the Shares which would be issued or
transferred if all Options granted and subsisting under the Scheme were exercised; or 

  

	 	(B)	by a resolution at a meeting of Option Holders or class of Option Holders passed by not less than 75 per cent (75%) of the Option Holders who attend and vote either in person or by proxy; 

and for the purpose of this Rule 16.1(d) the Option Holders or any class of Option Holders shall be treated as the holders of a separate class
of share capital and the provisions of the Articles of Association of the Company relating to class meetings shall apply mutatis mutandis. 
  

	16.2	Termination 

 The Scheme shall terminate upon the tenth anniversary of the Adoption Date
or at any earlier time by the passing of a resolution by the Directors. Termination shall be without prejudice to the subsisting rights of Option Holders. 
  

	16.3	Conflict with Schedule 5 

 If there is any conflict between the provisions of the Rules
as they apply to EMI Options and Schedule 5, Schedule 5 shall take precedence in respect of EMI Options. 
  

	16.4	Notices and documents 

  

	 	(a)	Option Holders not otherwise entitled thereto may at the discretion of the Company be sent copies of notices and other documents sent by the Company to its ordinary shareholders generally. 

 

	 	(b)	Written notice of any amendment made in accordance with this Rule 16 shall be given to those Option Holders affected by such amendment. 

  
 19 

	 	(c)	Any notice or other document required to be given hereunder to any Option Holder shall be delivered to him or sent by first class pre-paid post to him at his home address according to the records of the Company or such
other address as may appear to the Directors to be appropriate. Any notice or other document required to be given to the Directors shall be delivered to the Directors or sent by first class pre-paid post to the Directors at the Company’s
registered office or such other address as may be determined by the Directors to be appropriate. Notices sent by post to an Option Holder shall be deemed to have been given on the fifth day following the date of posting. 

 

	16.5	Disputes 

 The decision of the Directors in any dispute or question relating to any
Option shall be final and conclusive subject to the terms of this Scheme. 
  

	16.6	Governing Law 

 The Rules shall be governed by and construed in accordance with English
law. 
  

	16.7	Contracts (Rights of Third Parties) Act 1999 

 Except as expressly provided by the
Company, a person who is not the Option Holder or a Company who is not a member of the Group has no right under the Contracts (Rights of Third Parties) Act 1999 to rely upon or enforce any provisions of this Scheme, but this does not affect any
right or remedy of a third party which exists or is available apart from that Act. The Option Holder may not declare himself a trustee of his rights under this Scheme for the benefit of any third parties. 

 

	16.8	Data Protection 

 The Company and the Employer Company (if different) from time to time
will collect, hold and process the Option Holder’s personal information for the purposes of the administration of this Option. The Company will not use such personal information for any purpose other than the administration of the Option,
unless the Option Holder’s consent to that use is obtained. 
  

	17.	Overseas Employees 

 Notwithstanding any other provision of the Scheme the Board may
amend or add to the provisions of the Scheme and the terms of Option Agreements it considers necessary or desirable to take account of, or to mitigate, or to comply with relevant overseas taxation, securities or exchange control laws, provided that
the terms of Options granted to such Employees are not more favourable overall than the terms of Awards granted to other Employees. 
  

	18.	Supplementary Provisions 

 The Group shall not be liable to the Option Holder for any tax
or additional tax or national insurance payable by the Option Holder upon the exercise of an Option or upon the subsequent disposal of any Shares acquired upon exercise of the Option being tax or national insurance payable because of a failure to
qualify for relief under sections 529 to 532 of ITEPA in consequence of anything done by the Group. 

  
 20 

 SCHEDULE 1 

OPTION AGREEMENT FOR U.S. EMPLOYEES 
  

	
	THIS DOCUMENT IS IMPORTANT AND SHOULD BE KEPT IN A SAFE PLACE

 THIS OPTION AGREEMENT is made the [date] 2011 

BETWEEN 
  

	(1)	MIMECAST LIMITED (registered number 04698693) whose registered address is at 2-8 Balfe Street, London, N1 9EG; and 

  

	(2)	NAME of [ADDRESS] (the “Option Holder”) 

 SUPPLEMENTAL to the rules of the Mimecast
Limited 2010 EMI Share Option Scheme (the “Scheme”). Any words or expressions used in this option agreement and defined by the Scheme shall bear the same meaning in this agreement. 

INTRODUCTION: 
  

	(A)	The Company intends to grant an Option to the Option Holder. 

  

	(B)	The Option is intended to be an unapproved option. 

 AGREED TERMS 

 

	1.	Grant 

 The Company GRANTS an [EMI option/unapproved option] to the Option Holder
and the Option Holder AGREES to be bound in all respects by the provisions of the Scheme and ACCEPTS the grant on the terms set out in their agreement. 
  

	2.	Terms of the Scheme 

  

	2.1	Under the terms of the Scheme the Option Holder may acquire the number of ordinary shares (“Shares”) in the Company stated in clause 6(a) at the Option price per Share set out in clause 6.1. The Option price
per Share shall not be less than the “fair market value” as determined in good faith by the Directors, consistent with any method that is considered reasonable for purposes of determinations of fair market value under U. S. Internal
Revenue Code Section 409A and the regulations and applicable guidance thereunder (“Code Section 409A”). 

  

	2.2	The Option is granted and exercisable subject to the terms and conditions set out in the Scheme and in this Option Agreement. 

  
 21 

	3.	Memorandum and articles 

 Any Shares allotted or transferred pursuant to the exercise of
the Option are subject to the memorandum and articles of association of the Company (as amended from time to time) and to any necessary consents of any governmental or other authorities under any enactments from time to time in force. 

 

	4.	Non transferable 

 The Option is personal to the Option Holder and is not transferable,
assignable or chargeable. In addition, any Shares received upon exercise of an Option may be sold only on an exit event set out in Rule 12, or as otherwise provided in the Plan, and will be subject to sale restrictions following an exit event
analogous to the restrictions on exercise set forth in the Plan, including paragraphs (c) and (d) of Rule 12.3. 
  

	5.	Vesting and Exercise 

 The Option shall vest and, notwithstanding Rule 9.1(b), shall
become exercisable as follows: 
 25% of the Options shall be vested and exercisable on the first anniversary of the Date of Grant and
thereafter 6.25% of the Options shall be vested and exercisable at the expiry of 3 months from such anniversary and at the expiry of every subsequent 3 months period until the Options are fully vested on the fourth anniversary of the Date of Grant.

 In addition, the Option may become exercisable as provided in Rule 9 or Rule 12. The Option shall not be exercisable on or after the 10th Anniversary of the date of grant of the Original Option. 
  

	6.	Grant 

  

	6.1	The details of the grant are as follows; namely 

  

							
	(a)	  	  Number of Shares subject to the Option	  	      [amount].	  	
				
	(b)	  	  Option price per Share	  	      £[amount].	  	
				
	(c)	  	  Date of grant	  	      [date].	  	
				
	(d)	  	  Vesting Commencement Date	  	      [date].	  	

  

	6.2	The Option Holder irrevocably agrees to reimburse the Relevant Company for any Employer’s NICs arising on the exercise of an Option; or agrees to enter into an election with the Relevant Company to assume the
liability for any Employer’s NICs, payable on the exercise of the Option, including an election under paragraph 3B of Schedule 1 to the Social Security Contributions and Benefits Act 1992. 

 

	6.3	The exercise of the Option shall be conditional upon the Option Holder making good any Tax Liability in relation to the Option, or entering into arrangements acceptable to the Company in respect of such Tax Liability,
in accordance with rule 10.4 of the Scheme. 

  
 22 

	6.4	Any adjustment to this Option pursuant to Rule 15 of the Plan shall be made in accordance with the requirements for the adjustment of stock rights prescribed under Section 409A so as to qualify and maintain the
Option’s exemption from application of such provision. Similarly, the qualifying requirements for any Replacement Option issued in respect of this Option, as described under under Rule 13.4 of the Plan, shall comply with the
requirements for substitutions and assumptions of stock rights prescribed under Code Section 409A so as to qualify and maintain the Option’s exemption from application of such provision. 

  
 23 

 This option agreement has been executed as a deed and unconditionally delivered on the date first above written.

  

					
	SIGNED as a DEED	  	)	  	
	By MIMECAST LIMITED acting by    	  	)	  	
			
		  		  	 Director

			
	Signature of Witness:	  		  	
			
	Name of Witness:	  		  	
			
	Address:	  		  	
			
	Occupation:	  		  	
			
	SIGNED as a DEED	  	)	  	
	By [Option Holder]	  	)	  	
			
	Signature of Witness:	  		  	
			
	Name of Witness:	  		  	
			
	Address:	  		  	
			
	Occupation:	  		  	

  
 24 

 SCHEDULE 2 

NOTICE OF EXERCISE 
 TO:
    The Secretary, Mimecast Limited 
 I/We, being the holder or the Personal Representative(s) of the holder,* of the option granted in
the Option Certificate overleaf (“the Option”): 
  

	2.1	hereby exercise the Option to acquire                  ordinary shares in Mimecast Limited (“the Shares”) at a price of
£[●] per ordinary share, subject to the provisions contained in an Option Agreement dated [●] (“the Agreement”) made pursuant to the Mimecast Limited 2010 EMI Share Option Scheme and made between Mimecast Limited
and [●]; 

  

	2.2	enclose a cheque for the total price of the Shares (£            ) in favour of Mimecast Limited (“the Company”) and crossed
“a/c payee”, or such other documentation in respect of bridging finance or undertaking to procure payment as may be agreed by the Directors; 

 

	2.3	authorise and request you to enter my/our name(s) in the Company’s Register of Members as the holder(s) of the Shares, subject to the Company’s Memorandum and articles of association; 

 

	2.4	hereby covenant to pay the Company the amount of any Tax Liability** which may arise as a consequence of or in connection with this exercise of the Option (and, for the purposes of this Notice of Exercise, the
expression “Tax Liability” has the same meaning as it has in the Agreement; 

  

	2.5	in order to give effect to this covenant, I/we hereby authorise and appoint the Company as my/our attorney in my/our name(s) and on my/our behalf: 

 

	 	(a)	to sell such number (but no more) of the Shares registered in my/our name(s) as will enable the Company (after payment of all necessary selling expenses and commissions) to recover and retain for itself from the sale
proceeds an amount equal to such Tax Liability and then account to me/us for any cash balance remaining, provided that the Company may sell that number of shares at such price or prices as it shall, in its absolute discretion, consider fair and
reasonable, and 

  

	 	(b)	generally to sign any stock transfer form or other document or documents which may be required and to do any other thing which the Company shall consider necessary or expedient for carrying out the acts hereby
authorised in the same manner and as fully in all respects as I/we could have done personally and I/we hereby undertake to ratify everything which the Company shall do or purport to do by virtue of this power of attorney; and 

 

	2.6	request you to send a share certificate in respect of the Shares not sold pursuant to the authority given above (and, if appropriate, a balance option certificate) to me/us at the address given below. 

SIGNED and DELIVERED as a DEED BY 
  

									
	Name	 	  
	 		 	Address	 	  

					
	Signature	 	  
	 		 		 	  

					
	Date	 	  
	 		 		 	
					
	in the presence of:-  	 		 		 		 	
					
	Witness’ Name	 	  
	 		 	Address	 	  

					
	Witness’ Signature	 	  
	 		 		 	  

  

	*	Personal Representatives should enclose an Office Copy of the relevant Grant of Probate or Letters of Administration. 

	**	Persons exercising the option should consult with the Company as to whether any Tax Liability is anticipated, however the Company does not undertake to advise you on the tax consequences of exercising your Option. If
you are unsure of the tax liabilities which may arise you should take appropriate professional advice before exercising your Option. 

  
 25 

 DATED 

 
  

RULES OF 
 THE MIMECAST
LIMITED 2010 SHARE OPTION SCHEME FOR SOUTH AFRICAN EMPLOYEES 
 (approved by the Board on March 23 2010) 

(amended by the Board on 13 May 2014) 
  

 
  
 

 
 Berlin, Brussels, Cambridge, Dubai, Düsseldorf, Frankfurt, Hamburg, London, Munich, Paris. 

Representative offices: Alicante, Beijing, Shanghai. Associated office: Warsaw 

 Index 
  

							
	Clause No.	  	Page No.	 
			
	1.	 	Interpretation and Construction	  	 	3	  
			
	2.	 	Statement of Purpose	  	 	7	  
			
	3.	 	Grant of Options	  	 	7	  
			
	4.	 	Notice of Grant	  	 	8	  
			
	5.	 	EMI Options: Limit for individual Eligible Employee	  	 	9	  
			
	6.	 	Overall limits for Company on the Grant of Options	  	 	9	  
			
	7.	 	Ordinary Share Capital	  	 	9	  
			
	8.	 	Non-Transferable	  	 	9	  
			
	9.	 	Rights to Exercise Options	  	 	10	  
			
	10.	 	Exercise of Options	  	 	11	  
			
	11.	 	Lapse of Options	  	 	13	  
			
	12.	 	Takeover, Reconstruction, Liquidation and Sale of the Business	  	 	13	  
			
	13.	 	Replacement Options	  	 	15	  
			
	14.	 	Loss of Office or Employment	  	 	17	  
			
	15.	 	Adjustments	  	 	18	  
			
	16.	 	General	  	 	18	  
			
	17.	 	Overseas Employees	  	 	20	  
			
	18.	 	Supplementary Provisions	  	 	20	  
		
	SCHEDULE 1	  	 	21	  
		
	SCHEDULE 2	  	 	22	  

  
 2 

	1.	Interpretation and Construction 

  

	1.1	Definitions 

 In the Rules, unless the context requires otherwise, the following words
and expressions are defined or otherwise explained by the provisions indicated: 
  

	 “Acquiring Company” 
	any company which has obtained Control of the Company in accordance with any of the provisions of Rule 12; 

  

	 “Adoption Date” 
	the date on which the Rules are adopted by the Directors; 

  

	 “Bad Leaver” 
	any director or employee of any Group Company who ceases to be a director or employee without becoming a director or employee of any other Group Company and is not a Good Leaver; 

 

	 “Committed Time” 
	the meaning given by paragraph 26 of Schedule 5; 

  

	 “Companies Act” 
	the Companies Act 2006; 

  

	 “Company” 
	Mimecast Limited (registered number 04698693) whose registered address is at 2-8 Balfe Street, London, N1 9EG; 

  

	 “Control” 
	the meaning given by section 995 of the Tax Act; 

  

	 “Date of Grant” 
	the date on which an Option is granted to an Employee; 

  

	 “Directors” 
	the board of Directors of the Company or a duly authorised committee thereof; 

  

	 “Disqualifying Event” 
	the meaning given by Sections 534 to 536 of ITEPA; 

  

	 “Eligible Employee” 
	any person who is an employee of the Company or any Qualifying Subsidiary PROVIDED THAT where an Option is intended to be an EMI Option the Employee is an individual; 

 

	 	(a)	whose Committed Time amounts to at least 25 hours a week, or if less, 75% of his Working Time; and 

  

	 	(b)	who does not have a Material Interest in any Group Company; 

  

	 “EMI” 
	Enterprise Management Incentive; 

  

	 “EMI Option” 
	any right to acquire Shares: 

  

	 	(a)	in relation to which the requirements of Schedule 5 are met at the Date of Grant; and 

  
 3 

	 	(b)	of which Notice of Grant is given to HM Revenue & Customs in accordance with paragraph 44 of Schedule 5; 

  

	 	and, where the circumstances permit, a Replacement Option in relation to that EMI Option; 

  

	 “Employee” 
	any individual who is an employee of a Group Company; 

  

	 “Employer Company” 
	the company by reference to which the Option Holder is an Eligible Employee or Employee; 

  

	 “Employer’s NICs” 
	secondary Class 1 national insurance contributions; 

  

	 “Exercise Conditions” 
	any performance conditions set by the Directors under rule 3.4; 

  

	 “Exercise Period” 
	the period during which an Option may be exercised, which in any event shall terminate no later than the day before the 10th anniversary of the Date of Grant; 

 

	 “Good Leaver” 
	any director or any employee of any Group Company who ceases to be a director or employee without becoming a director or employee of any other Group Company by reason of injury or disability or in any other circumstance where the Directors, in
their absolute discretion, determine the director or employee to be a Good Leaver; 

  

	 “Group” and “Group Company” 
	“group”, in relation to a Parent Company, means that company and its Subsidiaries and “Group Company” shall be construed accordingly; 

  

	 “Independence Requirement” 
	the meaning given by paragraph 9 of Schedule 5; 

  

	 “ITEPA” 
	the Income Tax (Earnings and Pensions) Act 2003; 

  

	 “Market Value” 
	shall be determined in accordance with Part VIII of the Taxation of Chargeable Gains Act 1992; 

  

	 “Material Interest” 
	the meaning given by paragraph 29 of Schedule 5; 

  

	 “Notice of Exercise” 
	a notice of exercise in accordance with the form set out in Schedule 2 of the Rules or such other form as may be prescribed or required by the Directors from time to time; 

 

	 “Notice of Grant” 
	the notice of grant of the EMI Option issued by the Employer Company to HM Revenue & Customs in accordance with Rule 4.1; 

  

	 “Option” 
	a right to acquire Shares which shall include an EMI Option or an Unapproved Option; 

  
 4 

	 “Option Agreement” 
	an agreement between the Company and an Eligible Employee (or the Company and an Employee) which shall evidence the grant of the Option, which shall be in accordance with the Rules of the Scheme and which shall be in such form as may be
prescribed by the Directors; 

  

	 “Option Holder” 
	an Eligible Employee who has been granted an EMI Option or an Employee who has been granted an Unapproved Option (or his legal personal representatives where the circumstances permit); 

 

	 “Option Price” 
	the price per Share determined by the Directors which shall not be less than the Market Value of a Share on the Date of Grant and, in the case of an Option which is a right to subscribe for Shares, not less than the nominal value of a Share;

  

	 “Ordinary Share Capital” 
	the meaning given by section 989 of the Tax Act; 

  

	 “Parent Company” 
	a company that has one or more Subsidiaries; 

  

	 “Personal Representatives” 
	in relation to an Option Holder, the Option Holder’s legal personal representatives (being either the executors of his will to whom a valid grant of probate has been made or the duly appointed administrators of his estate) who in either
case have provided the Directors with satisfactory evidence of their appointment; 

  

	 “Qualifying Exchange” 
	an exchange of Shares in accordance with Rule 13.3; 

  

	 “Qualifying Subsidiary”  
	the meaning given by paragraph 11 of Schedule 5 to ITEPA; 

  

	 “Relevant Company” 
	the company (being either the Company or any Group Company) which incurs a Tax Liability as set out in Rule 10.4; 

  

	 “Replacement Option” 
	an Option granted in accordance with Rule 13; 

  

	 “Restrictions” 
	any condition attaching to the Shares which makes the interest in the Shares restricted within the meaning of Chapter 2 of Part VII of ITEPA; 

  

	 “Rules” 
	these rules together with any schedules or appendices to these rules; 

  

	 “Sale of the Business” 
	any transfer (whether through a single transaction or a series of transactions) of all or substantially all of the assets or undertaking of the Group (including goodwill) to any person (or persons connected with each other or act in concert with
each other); 

  

	 “Scheme” 
	this scheme as governed by the Rules; 

  

	 “Scheme of Reconstruction” 
	the meaning given by Rule 12.3; 

  
 5 

	 “Section 431 Election” 
	means an election in accordance with Section 431 of ITEPA being in the form as set out in Schedule 4 to this Scheme or in such other form as HM Revenue & Customs may determine from time to time; 

 

	 “Share” 
	Ordinary Shares in the capital of the Company (and in the context of an EMI Option, which satisfies the requirements of paragraph 35 of Schedule 5); 

  

	 “Schedule 5” 
	Schedule 5 to ITEPA; 

  

	 “Subsidiary”  
	means any body corporate which is a subsidiary of the Company within the meaning of section 1159 of the Companies Act 2006. 

  

	 “Tax Liability” 
	a liability to account for any employee’s tax, national insurance, social security or other levies in respect of the Option (including Employer’s NICs or equivalent employer’s social security contributions) (whether by reason of
grant, exercise, or otherwise or by reason of a Disqualifying Event in relation to EMI Options only), including for the avoidance of doubt and without limitation any liability arising after the termination of the Option Holder’s employment for
whatever reason and which: 

  

	 	(a)	may arise or be incurred in any jurisdiction whatsoever and, 

  

	 	(b)	by the law of the same jurisdiction may or shall be recovered from the person entitled to the Option; 

  

	 “Tax Act” 
	the Income Tax Act 2007; 

  

	 “Trading Activities Requirement” 
	the meaning given by paragraph 13 to 14 of Schedule 5; 

  

	 “Unapproved Options” 
	any right to acquire Shares granted pursuant to this Scheme which does not satisfy the requirements of Schedule 5; 

  

	 “Unvested” 
	such number or the proportion of the Shares subject to an Option that are not Vested; 

  

	 “Vested” 
	such number or the proportion of the Shares subject to an Option that shall become vested according to the Vesting Schedule and “Vest” shall be construed accordingly; 

 

	 “Vesting Schedule” 
	unless otherwise specified in the schedule in the Option Holder’s Option Agreement the Vesting Schedule shall be as follows: 

  

	 	 25% of the Options shall be vested on the first anniversary of the Date of Grant and thereafter 6.25% of the Options shall vest at the expiry of 3 months from

  
 6 

	 	 
such anniversary and at the expiry of every subsequent 3 months period until the Options are fully vested on the fourth anniversary of the Date of Grant. 

 

	 “Working Time” 
	the meaning given by paragraph 27 of Schedule 5; 

  

	 “Year” 
	a financial year of the Company. 

  

	1.2	Construction 

 Words or expressions used herein shall where appropriate: 

 

	 	(a)	when denoting the masculine gender include the feminine and vice-versa; 

  

	 	(b)	when denoting the singular include the plural and vice versa; 

  

	 	(c)	when referring to any enactment be construed as a reference to that enactment as for the time being consolidated, amended, re-enacted or replaced and shall include any regulations made thereunder; 

 

	 	(d)	when a period of time is specified and starts from a given day or the day of an act or event, be calculated exclusive of that day; and 

 

	 	(e)	be construed such that the headings and sub-headings are for ease of reference only, and do not affect the interpretation of any Rule; 

 

	 	(f)	be construed where not otherwise defined in the Rules to have the same meanings as in Schedule 5. 

  

	2.	Statement of Purpose 

 EMI Options granted at any time pursuant to the Rules are granted
for commercial reasons in order to recruit or retain an Eligible Employee and not as part of a scheme or arrangement the main purpose, or one of the main purposes, of which is the avoidance of tax. 

 

	3.	Grant of Options 

  

	3.1	General 

  

	 	(a)	Subject to the Rules, the Company may, at any time, grant 

  

	 	(i)	any Eligible Employee an EMI Option; or 

  

	 	(ii)	any Employee an Unapproved Option 

 over such number of Shares at such Option Price and with
such conditions of exercise as the Company may determine. 
  

	 	(b)	An EMI Option shall be granted in accordance with the provisions of Schedule 5. 

  

	 	(c)	EMI Options shall only be granted to individuals who are Eligible Employees. 

  
 7 

	 	(d)	Unapproved Options shall only be granted to individuals who are Employees. 

  

	 	(e)	An Option shall not be granted by any person other than the Company without the prior approval of the Directors. 

  

	3.2	Contents of Option Agreement 

 The Option shall be agreed in writing between the
Company and the Option Holder, and shall state: 
  

	 	(a)	the Date of Grant; 

  

	 	(b)	that the EMI Option is granted under the provisions of Schedule 5; 

  

	 	(c)	the number or maximum number of Shares over which the Option is granted; 

  

	 	(d)	the Option Price, or the method by which the Option Price is to be determined; 

  

	 	(e)	the Vesting Schedule; 

  

	 	(f)	the Exercise Period and; 

  

	 	(g)	details of any Restrictions attaching to the Shares and, if so, shall contain details of such Restrictions. 

  

	3.3	The Option Agreement for an Unapproved Option shall be in the same form as Rule 3.2 apart from Rule 3.2(b) and (g) which shall not apply. 

 

	3.4	The Directors may at the Date of Grant impose such performance condition or performance conditions to be satisfied upon the exercise of an Option. Such performance conditions: 

 

	 	(a)	must be objective and stated in writing at the Date of Grant; 

  

	 	(b)	may not be waived, varied or amended by the Directors unless in accordance with the terms of such conditions or, where any waiver, variation or amendment is at the discretion of the Directors, it shall only be exercised
in a manner which the Directors have determined to be fair and reasonable and, if events happen which cause the Directors, acting fairly and reasonably, to consider that the waived, varied or amended condition would be appropriate and would result
in the waived, varied or amended condition being no easier and no more difficult to satisfy than the condition as it existed immediately prior to such waiver, variation or amendment. 

 

	4.	Notice of Grant 

  

	4.1	On the grant of an EMI Option, a Notice of Grant shall be given by the Employer Company to HM Revenue & Customs within 92 days of the Date of Grant (or such further or other period as HM Revenue &
Customs or statute may allow, permit or require) and shall: 

  

	 	(a)	be in the form set out in Schedule 3 of the Rules or in such form as required by HM Revenue & Customs from time to time; 

  

	 	(b)	contain a declaration by the Option Holder that he satisfies the Working Time requirement; 

  
 8 

	 	(c)	contain a declaration by a director or the secretary of the Employer Company that: 

  

	 	(i)	in his opinion the requirements of Schedule 5 are met; and 

  

	 	(ii)	the information provided is to the best of his knowledge correct and complete. 

  

	4.2	On the grant of an Unapproved Option a Notice of Grant shall not be required. 

  

	5.	EMI Options: Limit for individual Eligible Employee 

  

	5.1	The number of Shares over which an EMI Option may be granted to any one Eligible Employee shall be limited and take effect so that the total value of Shares (as determined by paragraphs 5(6) to (8) of Schedule 5)
subject to unexercised EMI Options granted to that Eligible Employee by the Company or any other Group Company does not exceed £1 less than £120,000 (or such other limit as may apply from time to time in paragraph 5 of Schedule 5), SAVE
WHERE an EMI Option is granted under the provisions of Part 6 (Company Reorganisation) of Schedule 5. 

  

	5.2	Provided that if an EMI Option exceeds the limit in Rule 5.1 the Option shall be treated as two Options, one shall be an EMI Option as to the number of Shares to the value of £1 less than the limit in Rule 5.1 and
the other Option relating to the excess shall be an Unapproved Option. 

  

	6.	Overall limits for Company on the Grant of Options 

  

	6.1	Subject to such adjustments as may be made in accordance with Rule 15, no Option shall be granted on any Date of Grant if as a result the total value of Shares of the Company (as determined by paragraphs 5(6) to
(8) of Schedule 5) in respect of which unexercised EMI Options exist would exceed £3 million or such other limit as may apply from time to time in paragraph 7 of Schedule 5. 

 

	6.2	For the purpose of the limit contained in Rule 6.1 above, any Option or right which has been released, cancelled or lapsed without being exercised shall be ignored. 

 

	6.3	If following the purported grant of an EMI Option the limit in Rule 6.1 would be exceeded such an Option shall not be an EMI Option insofar as it relates to the excess. 

 

	7.	Ordinary Share Capital 

  

	7.1	Availability of authorised capital and Shares 

 The Company shall at all
times keep available sufficient authorised and unissued Shares to satisfy the exercise to the full extent still possible of all Options which have neither lapsed nor been fully exercised taking account of any other obligations of the Company to
provide shares of the same class as Shares. 
  

	8.	Non-Transferable 

 Save as provided in Rule 9.4, no Option nor any right thereunder shall
be capable of being transferred, assigned or charged in any manner whatsoever. Upon any such purported transfer, assignment, or charge the Option shall immediately lapse and cease to be exercisable. 

  
 9 

	9.	Rights to Exercise Options 

  

	9.1	General 

 Subject to rules 9.2, 9.3, 9.4, 9.5 and 12 below an Option: 

 

	 	(a)	shall not be exercisable before it has Vested in accordance with the Vesting Schedule; and 

  

	 	(b)	shall not be exercisable until an exit event set out in rule 12, subject to the provisions of the Option Agreement and subject to the provisions in rule 12.3; 

 

	 	(c)	shall not be exercisable unless the Exercise Conditions (if any) (as waived, varied or amended) have been fulfilled to the satisfaction of the Directors; and 

 

	 	(d)	shall not be exercised later than the day before the tenth anniversary of the Date of Grant. 

  

	9.2	Termination of Employment 

 If the Option Holder is a Bad Leaver, the Option, whether
Vested and unexercised or Unvested shall lapse immediately on the date upon which the Option Holder ceases to hold employment or office within the Group, or in the case of gross misconduct, on the date of occurrence of such misconduct. 

 

	9.3	Good Leaver 

 If the Option Holder is a Good Leaver: 

 

	 	(a)	the Option shall be exercisable to the extent Vested as at the date of ceasing employment within 39 days of ceasing employment (provided that the Directors shall have the discretion to waive the Exercise Conditions (if
any) relating to such Option); 

  

	 	(b)	the Option to the extent Unvested shall lapse immediately on the date upon which the Option Holder ceases employment, unless the Directors in their discretion determine before cessation that the Unvested Option may be
exercised within 39 days of ceasing employment. 

  

	9.4	Death of the Option Holder 

 If an Option Holder dies, the Option shall be exercisable to
the extent Vested as at the date of the Option Holder’s death by the Personal Representatives, provided that the Option shall only be exercisable within 12 months of the Option Holder’s death (and provided that the Directors shall have the
discretion to waive the Exercise Conditions (if any) relating to such Option). To the extent that the Option is Unvested the Option shall lapse on the date of the Option Holder’s death. 

 

	9.5	Admission to Main Market of London Stock Exchange, AIM or other securities exchange – for Options granted before 13 May 2014 only 

If the Company’s shares are admitted to listing on the Main Market of the London Stock Exchange, AIM or any other securities exchange, the
Option shall Vest in full immediately after the admission date (notwithstanding that part of the Option may be Unvested). The Option will be exercisable (subject to the discretion of the Board to permit an earlier exercise) as follows: 

 

	 	(a)	25% immediately following the admission date; 

  
 10 

	 	(b)	a further 50% on the first anniversary of the admission date; 

  

	 	(c)	a further 25% on the second anniversary of the admission date. 

  

	9.6	Admission to Main Market of London Stock Exchange, AIM or other securities exchange – for Options granted on or after 13 May 2014 

For the avoidance of doubt, Rule 9.5 shall not apply to all Options granted on or after 13 May 2014 and on admission vesting shall
continue as detailed in the Vesting Schedule and an Option may be exercised to the extent Vested during such periods as the Directors shall determine in their discretion. 
  

	10.	Exercise of Options 

  

	10.1	Procedure on exercise 

 An Option shall be exercisable, in whole or in part, by the
delivery to the secretary of the Company of the following: 
  

	 	(a)	an Option Agreement covering all of the Shares over which the Option is then to be exercised; 

  

	 	(b)	the Notice of Exercise in the prescribed form duly completed and signed by the Option Holder (or by his duly authorised agent); 

  

	 	(c)	a Section 431 Election (or a similar election should the Directors so require); 

  

	 	(d)	payment (in such manner as the Directors shall permit) of a sum equal to the aggregate Option Price for the number of Shares over which the Option is to be exercised; 

 

	 	(e)	payment (in such manner as the Directors shall permit) of any Tax Liability including Employer’s NICs in accordance with Rule 10.4; and 

 

	 	(f)	if there is a shareholders’ agreement or other such document (which contains restrictions on the Shares), is accompanied by a deed of adherence, in a form acceptable to the Company and executed by the Option
Holder, whereby the Option Holder agrees to be bound by the terms of such shareholders’ agreement or other such document. 

  

	10.2	Issue or transfer of Shares 

 The Company shall issue or procure the transfer of Shares
to be allotted or transferred pursuant to the exercise of an Option to the Option Holder such number of Shares within 30 days following the effective date of exercise of the Option. 

 

	10.3	Shares issued pursuant to the Scheme will rank pari passu in all respects with the Shares then already in issue except that they and any Shares transferred pursuant to the Scheme will not rank for any dividend or other
distribution of the Company paid or made by reference to a record date falling prior to the date of receipt of the Notice of Exercise of the Option pursuant to Rule 10.1. 

 

	10.4	Deductions 

  

	 	(a)	 Where in relation to Options, the Company or any Group Company (“the Relevant Company”) is liable, or is in accordance with current practice
believed to be liable under any statute or regulation or otherwise, to account to any 

  
 11 

	 	
revenue or other authority for sums in respect of a Tax Liability in relation to the Option, the Option Holder shall indemnify and shall keep indemnified the Relevant Company for the Tax
Liability and the Option Holder shall pay the Relevant Company a sum equal to the Tax Liability immediately upon written notice of the quantum of the said liability. 

 

	 	(b)	Notwithstanding the above, the Company may impose such conditions upon the exercise of the Options as are necessary to ensure that the Relevant Company is able to meet any or all of such liabilities, including, without
limitation, a condition that no exercise may take place unless the Option Holder has provided the Relevant Company with cash funds sufficient to meet such Tax Liability, or has entered into arrangements acceptable to the Relevant Company to secure
that such cash funds are available, or to allow the Relevant Company to deduct the amount of such Tax Liability from any cash amounts (including salary and bonuses) which may become payable to the Option Holder by any Group Company.

  

	 	(c)	The Company may require the Option Holder as a condition of the exercise of any Option that the Option Holder shall: 

  

	 	(i)	agree to reimburse the Relevant Company for any Employer’s NICs arising on the exercise of an Option; or 

  

	 	(ii)	enter into an election with the Relevant Company to assume the liability for any Employer’s NICs, payable on the exercise of the Option, including an election under paragraph 3B of Schedule 1 to the Social Security
Contributions and Benefits Act 1992; OR 

  

	 	(iii)	agree to pay the employer’s social security contributions, to the extent permitted by law, in any other jurisdiction. 

  

	 	(d)	If the Option Holder shall fail to: 

  

	 	(i)	make payment to the Relevant Company immediately upon receipt of a written notice in accordance with Rule 10.4(a); or 

  

	 	(ii)	reimburse the Relevant Company in accordance with an agreement or election in whole or in part for any liability to employer’s secondary national insurance contributions or employer’s social security
contributions pursuant to Rule 10.4(c); 

 then the Company shall be authorised by the Option Holder to reduce the number of
Shares otherwise deliverable to the Option Holder upon the exercise of an Option as may be sufficient to produce a sum which (after allowance for the costs and expenses of such a sale) may discharge (and shall be applied in discharge of) the Option
Holder’s liability to the Relevant Company under Rule 10.4(a) or any agreement or election pursuant to Rule 10.4(c) and the Company may exercise all such powers and may appoint any of its officers to sign all such documents in the name of the
Option Holder and as his act and deed as may be necessary for this purpose. 
  

	 	(e)	If the Option Holder shall fail to make payment to the Relevant Company immediately upon receipt of a written notice in accordance with Rule 10.4(a) then the Option Holder shall be liable to make good any amount
outstanding on demand. 

  
 12 

	11.	Lapse of Options 

  

	11.1	General 

 An Option shall immediately cease to be exercisable and shall lapse on the
earliest of: 
  

	 	(a)	the tenth anniversary of the Date of Grant; 

  

	 	(b)	the date upon which the Option Holder ceases to hold employment or office within the Group if the Option Holder is a Bad Leaver; 

  

	 	(c)	the expiry of the period in Rule 9.3, except that if the Option Holder dies during the exercise period specified in Rule 9.3, an Option shall not lapse by reason of this Rule 11.1 (c) until the first anniversary of
the Option Holder’s death, if later; 

  

	 	(d)	the first anniversary of the Option Holder’s death; 

  

	 	(e)	subject to Rule 13.1, the expiry of any of the periods referred to in Rule 12; 

  

	 	(f)	the date on which it is purported to be transferred or assigned (other than by reason of death in accordance with Rule 9.4), mortgaged, charged or otherwise disposed of by the Option Holder; 

 

	 	(g)	the presentation of any petition to any court of competent jurisdiction by which an order is sought for the bankruptcy of the Option Holder; 

 

	 	(h)	upon the Option Holder making an application for an interim order or any proposal for a voluntary arrangement within Part VIII of the Insolvency Act 1986; 

 

	 	(i)	upon the Option Holder proposing any form of compromise with his creditors or any class of creditors; and 

  

	 	(j)	the date on which the Option Holder is deprived (otherwise than on death) of the legal or beneficial ownership of the Option by operation of law or by the Option Holder doing or omitting to do anything which causes him
to be so deprived. 

  

	12.	Takeover, Reconstruction, Liquidation and Sale of the Business 

  

	12.1	General Offer 

 If any person obtains Control of the Company as a result of: 

 

	 	(a)	making an offer to acquire the whole of the issued share capital of the Company which is made on a condition such that, if it is satisfied, the person making the offer will have Control of the Company; or

  

	 	(b)	negotiating a share sale and purchase agreement with the shareholders of the Company which contemplates that the person will obtain Control of the Company on completion; 

(“a General Offer”), an Option may be exercised in accordance with the provisions in rule 12.3, to the extent Vested and to the
extent that the Exercise Conditions (if any) have been satisfied (and 75% of the Unvested Option shall be regarded as Vested and the remaining 25% of the Unvested Option may only be exercisable if the Directors determine that the circumstances
justify the exercise of a larger proportion than 75% of the Unvested Option). 

  
 13 

	12.2	Control 

 For the purposes of Rule 12.1 a person shall be deemed to have obtained Control
of the Company if he and others acting in concert with him have together obtained Control of it. 
  

	12.3	Exercise period for options and the offer of Replacement Options on a takeover 

  

	 	(a)	If Replacement Options are offered to all Option Holders by the Acquiring Company in relation to the Vested Options (including the Options which have been Vested due to the Change of Control) and an Option Holder does
not agree to release the Vested Options and accept the Replacement Option, the Board shall determine whether such Vested Options shall be exercisable in accordance with rule 12.3 (d) below or whether such Vested Options shall lapse.

  

	 	(b)	If Replacement Options are offered to all Option Holders by the Acquiring Company in relation to the Vested Options (including the Options which have been Vested due to the Change of Control) and an Option Holder does
agree to release the Vested Options and accept the Replacement Option, the terms of rule 13 shall apply to the Replacement Option. 

  

	 	(c)	If Replacement Options are not offered to all Option Holders then the Vested Options shall be exercisable in accordance with rule 12.3 (d) below. 

 

	 	(d)	In the circumstances set out in this rule 12.3, the Vested Options can be exercised in either of the following exercise periods determined by the Directors: - 

 

	 	(i)	Immediately before the change of Control becoming unconditional; or 

  

	 	(ii)	During a one month exercise period starting at a date to be determined by the Directors but such period to take place before the expiry of the 12 months period commencing on the change of Control becoming unconditional.

  

	12.4	Scheme of Reconstruction 

 If any person obtains Control of the Company in pursuance of a
compromise or arrangement sanctioned by the court under section 900 of the Companies Act or Article 418 of the Companies (Northern Ireland) Order 1986 (“a Scheme of Reconstruction”), an Option may be exercised to the extent Vested (and may
only be exercised to the extent Unvested if the Board in its discretion permits exercise) within 39 days of the court sanctioning the Scheme of Reconstruction. An Option shall not be exercisable after the said 39 days but may still be released under
Rule 13 within the period of six months following the court sanction of the Scheme of Reconstruction and, on the expiry of the said six month period, the Option shall lapse. 
  

	12.5	Chapter 3, Part 28 of the Companies Act 

 If any person becomes bound or entitled to
acquire shares under Chapter 3, Part 28 of the Companies Act, an Option may be exercised to the extent Vested (and may only be exercised to the extent Unvested if the Board in its discretion permits exercise) at any time when that person remains so
bound or entitled. 

  
 14 

	12.6	Liquidation 

 If a general meeting of the Company is called at which it is proposed to
pass a resolution for the voluntary winding up of the Company, the Company shall notify the Option Holder as soon as practicable of this fact. The Option may be exercised to the extent Vested (and may only be exercised to the extent Unvested if the
Board in its discretion permits exercise) during the period of such notice (such exercise being conditional on such resolution being passed and taking effect immediately thereafter) and such portion of the Option not otherwise exercised before such
resolution has been passed shall thereupon lapse. Where the Option Holder has exercised the Option pursuant to this Rule 12.6 and the resolution referred to above has been passed then (subject to the consent of the Company’s liquidator where
such is required by section 88 of the Insolvency Act 1986) the exercise of the Option shall take effect immediately and the Option Holder shall be entitled to share in the assets of the Company with the existing shareholders in the same manner as
the Option Holder would have been entitled had the Option Holder been the registered owner of the relevant Shares before the resolution was passed. 
  

	12.7	Reorganisation 

 An option may not be exercised under rule 12.1 if the General Offer is
part of a reorganisation so that the shareholders of the Acquiring Company hold their shares in the Acquiring Company in the same proportions as they held their shares in the Company. 

 

	12.8	Sale of Business 

 An Option may be exercised to the extent Vested (and may only be
exercised to the extent Unvested if the Board in its discretion permits exercise) within 39 days of a Sale of the Business and the Company shall notify the Option Holder as soon as practicable of this fact. 

 

	13.	Replacement Options 

  

	13.1	Grant of Replacement Options 

 If any company (“the Acquiring Company”): 

 

	 	(a)	obtains Control of the Company as a result of making a General Offer in accordance with Rule 12.1; or 

  

	 	(b)	obtains Control of the Company as a result of a Scheme of Reconstruction in accordance with Rule 12.3; or 

  

	 	(c)	becomes bound or entitled to acquire the Shares under Chapter 3, Part 28 of the Companies Act in accordance with Rule 12.4, or 

  

	 	(d)	obtains all the Shares as a result of a Qualifying Exchange within Rule 13.3, 

 an Option Holder
may at any time within the period set out in Rule 13.2, by agreement with the Acquiring Company, release any Option which has not lapsed (“the Old Option”) in consideration of the grant to him of an Option (“the New Option”)
which is equivalent to the Old Option but relates to shares in the Acquiring Company and qualifies as a Replacement Option as set out in rules 13.4 and 13.5. 

  
 15 

	13.2	Period within which Replacement Option to be granted 

 The New Option must be granted
within the following periods: 
  

	 	(a)	if the change of Control is by reason of a general offer in accordance with Rule 12.1, the period of six months beginning with the time when the person making the offer has obtained control of the Company and any
condition subject to which the offer is made is satisfied; 

  

	 	(b)	if the change of Control is by reason of a Scheme of Reconstruction (in accordance with Rule 12.3) or a Qualifying Exchange the period of six months beginning with the time when the Acquiring Company obtains Control of
the Company whose shares are subject to the Old Option; 

  

	 	(c)	if the change of Control occurs under Chapter 3, Part 28 of the Companies Act, the period during which the Acquiring Company remains bound or entitled in accordance with those procedures. 

 

	13.3	Exchange of Shares 

  

	 	(a)	An exchange of shares will be treated as a Qualifying Exchange where arrangements are made in accordance with which a company (“the New Company”) acquires all the shares (“Old Shares”) in another
company (“the Old Company”) and the following conditions are met: 

  

	 	(i)	that the consideration for the Old Shares consists wholly of the issue of shares (“New Shares”) in the New Company; 

  

	 	(ii)	that New Shares are issued in consideration of Old Shares only at times when there are no issued shares in the New Company other than: 

 

	 	(A)	subscriber shares, and 

  

	 	(B)	New Shares previously issued in consideration of Old Shares; 

  

	 	(iii)	that the consideration for New Shares of each description consists wholly of Old Shares of the corresponding description; 

  

	 	(iv)	that New Shares of each description are issued to the holders of Old Shares of the corresponding description in respect of, and in proportion to, their holdings; and 

 

	 	(v)	that by virtue of section 127 of the Taxation of Chargeable Gains Act 1992 as applied by section 135(3) of that Act, the exchange of shares is not treated as involving a disposal of the Old Shares or an acquisition of
the New Shares. 

  

	 	(b)	For the purposes of this rule Old Shares and New Shares are of a corresponding description if, on the assumption that they were shares in the same company, they would be of the same class and carry the same rights, and
references to “shares”, except in the expression “subscriber shares”, includes securities. 

  

	13.4	Qualifying requirements for Replacement Option 

 Subject to Rule 13.5, a New Option
qualifies as a Replacement Option only if: 

  
 16 

	 	(a)	the New Option is granted to the Option Holder by reason of his employment: 

  

	 	(i)	with the Acquiring Company, or 

  

	 	(ii)	if that company is a Parent Company, with that company or another Group Company; 

  

	 	(b)	at the time of the release of rights under the Old Option, the purpose for granting the New Option is for commercial reasons in order to recruit or retain an Eligible Employee, and not as part of a scheme or arrangement
the main purpose, or one of the main purposes, of which is the avoidance of tax; 

  

	 	(c)	at that time, 

  

	 	(i)	the Independence Requirement and the Trading Activities Requirement are met in relation to the Acquiring Company; 

  

	 	(ii)	the individual to whom the New Option is granted is an Eligible Employee in relation to the Acquiring Company; and 

  

	 	(iii)	the New Option would satisfy the requirements of being an EMI Option set out in Part V of Schedule 5; 

  

	 	(d)	the total Market Value, immediately before the release, of the Shares which were subject to the Old Option is equal to the total Market Value, immediately after the grant, of the Shares in respect of which the New
Option is granted; and 

  

	 	(e)	the total amount payable by the employee for the acquisition of shares in pursuance of the New Option is equal to the total amount that would have been payable for the acquisition of shares in pursuance of the Old
Option. 

  

	13.5	Provided that a Replacement Option for an Unapproved Option shall not have to satisfy the requirements in Rule 13.4(b) and Rule 13.4(c). 

 

	13.6	Where, in accordance with this Rule 13, an Option is released and a New Option granted, the New Option shall not be exercisable in accordance with Rule 12 by virtue of the event which gave rise to the New Option being
granted. 

  

	14.	Loss of Office or Employment 

  

	14.1	The grant of an Option does not form part of the Option Holder’s entitlement to remuneration or benefits pursuant to his contract of employment nor does the existence of a contract of employment between an Eligible
Employee and any company give such Eligible Employee any right or entitlement to have an Option granted to him in respect of any number of Shares or any expectation that an Option might be granted to him whether subject to any conditions or at all
and the grant of an Option shall not give him any entitlement or expectation that further Options will be granted. 

  

	14.2	The rights and obligations of an Option Holder under the terms and conditions of his office or employment shall not be affected by his participation under the Rules or any right he may have to participate.

  

	14.3	 An individual who participates under the Rules waives all and any rights to compensation or damages in consequence of the termination of his office or
employment with any company for any reason whatsoever, whether lawful or not, in so 

  
 17 

	 	
far as those rights arise, or may arise, from his ceasing to have rights under or be entitled to exercise any Option under the Rules as a result of such termination or from the loss or diminution
of value of such rights or entitlements. If necessary, the Option Holder’s terms of employment shall be varied accordingly. 

  

	15.	Adjustments 

  

	15.1	General rule 

 The number of Shares over which an Option is granted and the Option Price
thereof shall be adjusted in such manner as the Directors shall determine following any capitalisation issue, rights issue, subdivision, consolidation or reduction of share capital of the Company or any other variation of share capital to the intent
that (as nearly as may be) the total Option Price multiplied by the number of Shares that is payable in respect of an Option shall remain unchanged. 
  

	15.2	Reduction of Option Price to below nominal value 

 Subject to Rule 15.3 below, an
adjustment may be made under Rule 15.1 above which would have the effect of reducing the Option Price of unissued shares to less than the nominal value of a Share, but only if, and to the extent that, the Directors shall be authorised to capitalise
from the reserves of the Company a sum equal to the amount by which the aggregate nominal value of the Shares in respect of which the Option is exercisable exceeds the aggregate adjusted Option Price, so that on exercise of any Option in respect of
which the Option Price has been reduced, the Directors shall capitalise and apply such sum (if any) as is necessary to pay up the amount by which the aggregate nominal value of the Shares in respect of which the Option is exercised exceeds the
aggregate Option Price for such Shares. 
  

	15.3	Option over issued and unissued Shares 

 Where an Option subsists over both issued and
unissued Shares, an adjustment permitted by Rule 15.2 above, may only be made if the reduction of the Option Price of both issued and unissued Shares can be made to the same extent. 

 

	15.4	Administrative steps 

 The Directors shall notify Option Holders of any adjustment made
under this Rule 15 as soon as reasonably practicable and may take such steps and the Company shall execute such documents as it considers necessary to give effect to such adjustment. Furthermore, and without limitation to the generality of the
foregoing, the Directors may call in, cancel, endorse, issue or reissue any Option Agreement subsequent upon such adjustment. 
  

	16.	General 

  

	16.1	Amendments 

  

	 	(a)	Subject to rules 16.1(b) to (d), the Directors shall have the discretion to: 

  

	 	(i)	amend or add to the Rules; and 

  

	 	(ii)	impose additional conditions or requirements on the Options or on the terms on which Shares are acquired. 

  
 18 

	 	(b)	No amendments may be made to the Rules which would have the effect of causing EMI Options to cease to be EMI Options. 

  

	 	(c)	The Directors may at any time make such alterations (including additions) to the Rules as are necessary to secure that the Rules as applicable to EMI Options are in accordance with Schedule 5 and continue to be in
accordance with Schedule 5. 

  

	 	(d)	No amendment or addition shall be made to the Rules which would abrogate or adversely affect the subsisting rights of Option Holders unless: 

 

	 	(i)	where the rights are enjoyed by a single Option Holder and are not enjoyed by any other Option Holder or class of Option Holders, it is made with the written consent of that Option Holder; or 

 

	 	(ii)	where the rights are enjoyed by all Option Holders or any class of Option Holders then: 

  

	 	(A)	with the consent in writing of such number of Option Holders or class of Option Holders (as the case may be) as hold Options under the Scheme to acquire 75 per cent (75%) of the Shares which would be issued or
transferred if all Options granted and subsisting under the Scheme were exercised; or 

  

	 	(B)	by a resolution at a meeting of Option Holders or class of Option Holders passed by not less than 75 per cent (75%) of the Option Holders who attend and vote either in person or by proxy; 

and for the purpose of this Rule 16.1(d) the Option Holders or any class of Option Holders shall be treated as the holders of a separate class
of share capital and the provisions of the Articles of Association of the Company relating to class meetings shall apply mutatis mutandis. 
  

	16.2	Termination 

 The Scheme shall terminate upon the tenth anniversary of the Adoption Date
or at any earlier time by the passing of a resolution by the Directors. Termination shall be without prejudice to the subsisting rights of Option Holders. 
  

	16.3	Conflict with Schedule 5 

 If there is any conflict between the provisions of the Rules
as they apply to EMI Options and Schedule 5, Schedule 5 shall take precedence in respect of EMI Options. 
  

	16.4	Notices and documents 

  

	 	(a)	Option Holders not otherwise entitled thereto may at the discretion of the Company be sent copies of notices and other documents sent by the Company to its ordinary shareholders generally. 

 

	 	(b)	Written notice of any amendment made in accordance with this Rule 16 shall be given to those Option Holders affected by such amendment. 

 

	 	(c)	 Any notice or other document required to be given hereunder to any Option Holder shall be delivered to him or sent by first class pre-paid post to him
at his home address according to the records of the Company or such other address as may appear to the Directors to be appropriate. Any notice or other 

  
 19 

	 	
document required to be given to the Directors shall be delivered to the Directors or sent by first class pre-paid post to the Directors at the Company’s registered office or such other
address as may be determined by the Directors to be appropriate. Notices sent by post to an Option Holder shall be deemed to have been given on the fifth day following the date of posting. 

 

	16.5	Disputes 

 The decision of the Directors in any dispute or question relating to any
Option shall be final and conclusive subject to the terms of this Scheme. 
  

	16.6	Governing Law 

 The Rules shall be governed by and construed in accordance with English
law. 
  

	16.7	Contracts (Rights of Third Parties) Act 1999 

 Except as expressly provided by the
Company, a person who is not the Option Holder or a Company who is not a member of the Group has no right under the Contracts (Rights of Third Parties) Act 1999 to rely upon or enforce any provisions of this Scheme, but this does not affect any
right or remedy of a third party which exists or is available apart from that Act. The Option Holder may not declare himself a trustee of his rights under this Scheme for the benefit of any third parties. 

 

	16.8	Data Protection 

 The Company and the Employer Company (if different) from time to time
will collect, hold and process the Option Holder’s personal information for the purposes of the administration of this Option. The Company will not use such personal information for any purpose other than the administration of the Option,
unless the Option Holder’s consent to that use is obtained. 
  

	17.	Overseas Employees 

 Notwithstanding any other provision of the Scheme the Board may
amend or add to the provisions of the Scheme and the terms of Option Agreements it considers necessary or desirable to take account of, or to mitigate, or to comply with relevant overseas taxation, securities or exchange control laws, provided that
the terms of Options granted to such Employees are not more favourable overall than the terms of Awards granted to other Employees. 
  

	18.	Supplementary Provisions 

 The Group shall not be liable to the Option Holder for any tax
or additional tax or national insurance payable by the Option Holder upon the exercise of an Option or upon the subsequent disposal of any Shares acquired upon exercise of the Option being tax or national insurance payable because of a failure to
qualify for relief under sections 529 to 532 of ITEPA in consequence of anything done by the Group. 

  
 20 

 SCHEDULE 1 

OPTION AGREEMENT 

  
 21 

 SCHEDULE 2 

NOTICE OF EXERCISE 

TO:    The Secretary, Mimecast Limited 

I/We, being the holder or the Personal Representative(s) of the holder,* of the option granted in the Option Certificate overleaf (“the
Option”): 
  

	2.1	hereby exercise the Option to acquire             ordinary shares in Mimecast Limited (“the Shares”) at a price of £[●] per
ordinary share, subject to the provisions contained in an Option Agreement dated [●] (“the Agreement”) made pursuant to the Mimecast Limited 2010 EMI Share Option Scheme and made between Mimecast Limited and [●];

  

	2.2	enclose a cheque for the total price of the Shares (£            ) in favour of Mimecast Limited (“the Company”) and crossed
“a/c payee”, or such other documentation in respect of bridging finance or undertaking to procure payment as may be agreed by the Directors; 

  

	2.3	authorise and request you to enter my/our name(s) in the Company’s Register of Members as the holder(s) of the Shares, subject to the Company’s Memorandum and articles of association; 

 

	2.4	hereby covenant to pay the Company the amount of any Tax Liability** which may arise as a consequence of or in connection with this exercise of the Option (and, for the purposes of this Notice of Exercise, the
expression “Tax Liability” has the same meaning as it has in the Agreement; 

  

	2.5	in order to give effect to this covenant, I/we hereby authorise and appoint the Company as my/our attorney in my/our name(s) and on my/our behalf: 

 

	 	(a)	to sell such number (but no more) of the Shares registered in my/our name(s) as will enable the Company (after payment of all necessary selling expenses and commissions) to recover and retain for itself from the sale
proceeds an amount equal to such Tax Liability and then account to me/us for any cash balance remaining, provided that the Company may sell that number of shares at such price or prices as it shall, in its absolute discretion, consider fair and
reasonable, and 

  

	 	(b)	generally to sign any stock transfer form or other document or documents which may be required and to do any other thing which the Company shall consider necessary or expedient for carrying out the acts hereby
authorised in the same manner and as fully in all respects as I/we could have done personally and I/we hereby undertake to ratify everything which the Company shall do or purport to do by virtue of this power of attorney; and 

 

	2.6	request you to send a share certificate in respect of the Shares not sold pursuant to the authority given above (and, if appropriate, a balance option certificate) to me/us at the address given below. 

SIGNED and DELIVERED as a DEED BY 
  

									
	Name	 	  
	 		 	Address	 	  

					
	Signature	 	  
	 		 		 	  

					
	Date	 	  
	 		 		 	
					
	in the presence of:-  	 		 		 		 	
					
	Witness’ Name	 	  
	 		 	Address	 	  

					
	Witness’ Signature	 	  
	 		 		 	  

  

	*	Personal Representatives should enclose an Office Copy of the relevant Grant of Probate or Letters of Administration. 

	**	Persons exercising the option should consult with the Company as to whether any Tax Liability is anticipated, however the Company does not undertake to advise you on the tax consequences of exercising your Option. If
you are unsure of the tax liabilities which may arise you should take appropriate professional advice before exercising your Option. 

  
 22 

 [DATE] 

STRICTLY CONFIDENTIAL 
 Dear [NAME] 

MIMECAST LIMITED 
 2010
EMI SHARE OPTION SCHEME 
 OPTION AGREEMENT 
  

	1.	Grant and operation of the Scheme 

  

	1.1	I am pleased to inform you that Mimecast South Africa (Pty) Ltd (your “Employer”, has nominated you as a participant in the Mimecast Limited (the “Company”) 2010 South Africa Share Option
Scheme (“the Scheme”). Accordingly, you are hereby awarded an option to acquire [0,000] Shares in the Company (the “Option”) with an exercise price of £[ ] per Share (the “Exercise Price”). 

 

	1.2	The Option is granted upon the terms specified in this letter (the “Letter”) and the rules of the Scheme (the “Rules”), attached hereto at Appendix C. 

 

	1.3	The Company’s Directors (the “Board”), or a committee of the Board, will administer the Scheme. 

  

	1.4	Upon signing the Notice of Acceptance, attached hereto at Appendix A, you undertake to comply with the terms of this Letter, the Scheme and the Rules. 

 

	1.5	This Letter and the Notice of Acceptance will, together with the Rules constitute the contract between yourself and the Company with regard to the Scheme, and it is recommended that you read the Rules carefully
to understand the terms and conditions thereof. 

  

	1.6	Capitalized words not defined in this Letter shall have the meaning ascribed in the Rules. 

  

	1.7	Should there be any conflict between the Rules and this Letter, the Rules will prevail. 

	2.	Grant 

  

	2.1	The Date of Grant of this Option is [DATE]. 

  

	2.2	The Option is personal to you and may only be exercised by you. It cannot be transferred, ceded, assigned or otherwise disposed of, except on your death and then in accordance with the Rules. 

 

	3.	Rights to exercise Options 

  

	3.1	You may exercise an Option granted pursuant to this Letter in accordance with Rule 9 

  

	3.2	In the event of a change of Control you will, in addition to the Rules, be subject to the drag and tag rights pursuant to the Company’s Articles of Association. 

 

	4.	Method of exercise 

  

	4.1	An Option shall be exercisable from time to time, in whole or in part, in accordance with the Rules and specifically, Rule 10.1, by completing the Notice of Exercise attached hereto as Appendix B.

  

	4.2	When you exercise your Option, you will be required to pay a sum equal to the aggregate Option Price for the number of Shares over which the Option is to be exercised using one of the following three methods:

  

	4.2.1	Sell all of the shares you exercise and use some of the proceeds to pay the Option Price due (“Sell All”); or 

  

	4.2.2	Sell sufficient of the shares you exercise to cover the Option Price. The balance of the shares will be released to you and registered in your name (“Sell Sufficient”); or 

 

	4.2.3	Fund the Option Price due from your own resources (“Self Fund”). 

  

	4.3	You should be aware that if you choose to Self Fund, you will have to obtain a tax clearance certificate and remit the Option Price in terms of your foreign investment allowance (R4,000,000 life time limit) in
terms of South African exchange control regulations. 

  

	4.4	 The Company shall issue or procure the transfer of Shares to be allotted or transferred pursuant to the exercise of an Option to the Option
Holder within 30 days following the effective date of exercise of the Option. No Shares shall be transferred into your name until you have concluded a deed of adherence in terms of which you agree to take assignment of and assume the rights and

	 	
obligations of a shareholder of the Company under the Shareholders’ Agreement, subject to certain exclusions specified in the deed of adherence, and be bound by the terms and conditions of
the Shareholders’ Agreement as if you were an original party thereto. 

  

	4.5	Shares issued pursuant to the Scheme will rank pari passu in all respects with the Shares then already in issue except that they and any Shares transferred pursuant to the Scheme will not rank for any dividend or
other distribution of the Company paid or made by reference to a record date falling prior to the date of receipt of the Notice of Exercise of the Option pursuant to Rule 10.1. 

 

	5.	Lapse of Options 

 An Option shall immediately cease to be exercisable and shall lapse on
the earliest of the occurrence of an event contained in Rule 11. 
  

	6.	Taxation of Awards 

  

	6.1	In terms of the prevailing tax legislation you will be liable for income tax on the difference between the market value of the underlying Shares on the date of exercise and the Option Price. Notwithstanding the method
of exercise elected, you will be responsible for the income tax (PAYE) and your employer has an income tax withholding and reporting obligation in respect of the PAYE, as explained below: 

 

	6.2	If you elect the Sell All alternative, your employer will withhold the PAYE from the cash proceed and pay the required PAYE over to the South African Revenue Services (“SAR”) 

 

	6.3	If you elect the Sell Sufficient alternative, and you only sell sufficient shares to cover the purchase price, you must either (i) sell more shares to cover the tax liability, or (ii) instruct your
employer to deduct the PAYE from your normal salary, or (iii) provide your employer with sufficient funds to cover the PAYE. If the taxable gain is more than your normal monthly salary or if you do not provide your employer with sufficient
funds, you will be obliged to sell sufficient shares to cover the PAYE. 

  

	6.4	If you elect the Self Fund alternative, you must either (i) instruct your employer to deduct the PAYE from your normal salary, or (ii) provide your employer with sufficient funds to cover the PAYE. If
the taxable gain is more than your normal monthly salary or if you do not provide your employer with sufficient funds, you will be obliged to sell sufficient shares to cover the PAYE. 

 Yours sincerely, 
  

	
	  

	 COMPANY SECRETARY

 APPENDIX A 

MIMECAST LIMITED 
 2010
EMI SHARE OPTION SCHEME 
 NOTICE OF ACCEPTANCE 

I, the undersigned, hereby accept the Option to acquire [0,000] shares in the Company subject to the terms and conditions set out in the Letter addressed to
me dated [        ] 2014 and the Rules of the Scheme, with which I am fully acquainted. 
 I hereby further
undertake, if and when called upon by any director or the Secretary of the Company to do so, to sign any further documents which may be considered necessary or desirable by the Company in order to give effect to the provisions of the Scheme. 

DATED AT
                                         THIS
             DAY OF
                                         
        2014. 
  

	
	  

	Signature of Optionee

 APPENDIX B 

2010 EMI SHARE OPTION SCHEME 

EXERCISE NOTICE 
  

	
	  

	(Date)

 Mimecast Limited 
 2-8
Balfe Street 
 London 
 N1 9EG 

Attention of the Chief Executive Officer/Secretary 

I,             , hereby subscribe for
            Class B shares of Mimecast Limited (the “Company”) by way of the exercise of the Option granted at an exercise price of
            under the terms of the Letter dated             between the undersigned and the Company in accordance with the terms
of the 2010 EMI Share Option Scheme. 
 In connection with the Exercise Price of [insert] which I am obliged to pay in order to exercise my Option, I hereby
elect to pay the Exercise Price as follows: 
 Please indicate the method you have chosen with an “X”. You should choose one only. 

 

	 ̈	Sell All. I authorise the Company to sell all of the shares due to me on the exercise of my Option and to deduct the Exercise Price from the proceeds of sale of those shares. I acknowledge that the net
proceeds of sale, after payment of the Exercise Price, will be paid to me. I have provided by bank details below. 

  

	 ̈	Sell Sufficient. I authorise the Company to sell sufficient of the shares due to me on the exercise of my Option to cover the Exercise Price and acknowledge that the balance of the shares will be released to me
and registered in my name. I have provided my share registration details below. 

  

	 ̈	Self Fund. I accept that I must fund the Exercise Price due from my own resources and enclose a cheque or money order made payable to Mimecast Ltd in this regard. I have provided my share registration
details below. 

 I have chosen to Sell All and my bank details are as follows: 

 

					
	Name of account:	 	  
	  	
			
	Bank:	 	  
	  	
			
	Bank account no.:      	 	  
	  	
			
	Branch:	 	  
	  	
			
	Branch code:	 	  
	  	

 I have chosen either to Sell Sufficient or Self Fund and my share registration details are as follows: 

 

					
	 Full name:            
	  	  
	  	
			
	 Address:
	  	  
	  	
			
		  	  
	  	

  

	
	  

	(Signature)
	
	  

	(Name)
	
	  

 APPENDIX C 

RULES OF THE MIMECAST LIMITED 2010 SOUTH AFRICA SHARE OPTION SCHEMEEX-10.8

 Exhibit 10.8 
  

 
 Mimecast Limited 

 
  

Rules of the Mimecast Limited Approved Share Option Plan 

Approved by the Board on 24 October 2012 

Approved by HM Revenue & Customs on 14 November 2012 

HM Revenue & Customs reference: X109220 

Amended by the Board on 13 May 2014 

Amended by the Compensation Committee of the Board on 28 April 2015 

 
  
  

			
	 5 New Street Square | London EC4A 3TW
 Tel +44
(0)20 7300 7000
 Fax +44 (0)20 7300 7100
 DX 41 London

www.taylorwessing.com
	 	 

							
	1.	  	Definitions	  	 	3	  
			
	2.	  	Grant of Options	  	 	5	  
			
	3.	  	Limit on value of Options	  	 	6	  
			
	4.	  	Rights of Exercise and lapse of Options	  	 	6	  
			
	5.	  	Lapse of Options	  	 	8	  
			
	6.	  	Takeover, Reconstruction, Winding-Up and Listing	  	 	8	  
			
	7.	  	Replacement Options	  	 	10	  
			
	8.	  	Manner of Exercise	  	 	10	  
			
	9.	  	Issue or Transfer of Shares	  	 	11	  
			
	10.	  	Adjustments	  	 	11	  
			
	11.	  	Administration	  	 	12	  
			
	12.	  	Alterations	  	 	13	  
			
	13.	  	General	  	 	13	  

  
 2 

	1.	Definitions 

  

	1.1	In this Plan, the following words and expressions shall have, where the context so admits, the meanings set forth below: 

“Appropriate Period” has the meaning given by paragraph 26(3) of Schedule 4; 

“Associated Company” has the meaning given by paragraph 35 of Schedule 4; 

“Board” means the board of directors for the time being of the Company or a duly authorised committee thereof; 

“Close Company” means a close company as defined in Section 989 of the Income Tax Act 2007 as varied by paragraph 9 of
Schedule 4; 
 “Committee” means a committee of the Board; 

“Company” means Mimecast Limited (registered number 04698693) whose registered address is at 2-8 Balfe Street, London, N1 9EG;

 “Constituent Company” means 
  

	 	(a)	the Company; and 

  

	 	(b)	any other company which is under the Control of the Company, is a Subsidiary of the Company and which has been expressly designated by the Board as being a Constituent Company; and 

 

	 	(c)	any other company which is a Jointly Owned Company and which has been expressly designated by the Board as being a Constituent Company; 

“Control” has the meaning given by Section 995 of the Income Tax Act 2007; 

“Date of Cessation” means the date on which a Participant ceases to hold an office or employment with a Constituent Company or
an Associated Company; 
 “Date of Death” means the date on which a Participant dies; 

“Date of Grant” means the date on which the Board grants an Option; 

“Dealing Day” means any day on which the London Stock Exchange is open for the transaction of business; 

“Eligible Employee” means any person who at the Date of Grant is: 

 

	 	(a)	a full-time director (required to work for not less than 25 hours per week, excluding meal breaks) or employee, of a Constituent Company; and 

 

	 	(b)	not precluded by paragraph 9 of Schedule 4 from participating in the Plan; 

“Employees’ Share Scheme” has the meaning given by Section 1166 of the Companies Act 2006; 

“Exercise Price” means the total amount payable in relation to the exercise of an Option, whether in whole or in part, being
an amount equal to the relevant Option Price multiplied by the number of Shares in respect of which the Option is exercised; 

  
 3 

 “Group Member” means the Company, any company under the Control of the Company
or any Associated Company; 
 “ITEPA” means the Income Tax (Earnings and Pensions) Act 2003; 

“Jointly Owned Company” means any company owned by the Company jointly with another person and any company controlled by such
jointly owned company within the meaning of Paragraph 34 of Schedule 4 ITEPA; 
 “London Stock Exchange” means the
London Stock Exchange plc; 
 “Market Value” means in relation to a Share on any day: 

 

	 	(a)	if and so long as the Shares are fully quoted on the London Stock Exchange, its middle market quotation (as derived from the Daily Official List of the London Stock Exchange); 

 

	 	(b)	subject to (a) above, its market value, determined in accordance with Part VIII of the Taxation of Chargeable Gains Act 1992 agreed in advance with the Shares and Assets Valuation of HM Revenue & Customs;

 “Material Interest” has the meaning given by paragraph 10 of Schedule 4; 

“Member of a Consortium” has he meaning given by paragraph 36(2) of Schedule 4; 

“Option” means a right to acquire Shares under the Plan; 

“Option Price” means the price per Share, as determined by the Board, at which an Eligible Employee may acquire Shares upon
the exercise of an Option granted to him being not less than the higher of: 
  

	 	(a)	the Market Value of a Share on the Dealing Day immediately preceding the Date of Grant (or, if the Committee determines, the average of the Market Values on the three Dealing Days immediately preceding the Date of Grant
); and 

  

	 	(b)	if the Shares are to be subscribed, their nominal value; but subject to any adjustment pursuant to Rule 8; 

“Participant” means any Eligible Employee to whom an Option has been granted, or (where the context so admits) the personal
representative(s) of any such person; 
 “PAYE Liability” means the amount (if any) of:  

 

	 	(a)	income tax payable by deduction under Part 11 of ITEPA (PAYE); 

  

	 	(b)	primary Class 1 National Insurance Contributions (“NIC”); 

  

	 	(c)	all or such part (as may from time to time be agreed in writing between the Participant and the Company (or the Participant’s employing company)) of any secondary Class 1 NIC payable in respect of any gain which is
treated as remuneration derived from the Participant’s employment for NIC purposes by virtue of Section 4(4)(a) of the Social Security Contributions and Benefits Act 1992 (as amended); or 

 

	 	(d)	any other similar taxes or duties, which a Constituent Company or other Group Member would be required to account for to HM Revenue & Customs or other taxation authority if a Participant exercised an Option;

  
 4 

 “Retirement” means retirement on or after the age of [65] years; 

“Schedule 4” means Schedule 4 to ITEPA; 

“Plan” means the Mimecast Limited Approved Share Option Plan which has been approved by HM Revenue & Customs in
accordance with Schedule 4, in its present form or as from time to time amended in accordance with the provisions hereof; 

“Share” means a fully paid ordinary share in the capital of the Company which satisfies paragraphs 16 to 20 of Schedule 4;

 “Subsidiary” means a company as defined by Section 1159 of the Companies Act 2006; and 

“Vesting Commencement Date” shall mean the Date of Grant or other date from which vesting shall be determined as specified by
the Board on the Date of Grant, provided that such date shall be no earlier than one year prior to the Date of Grant; 
 “Vesting
Schedule” means the that the Option shall vest as to 25% of the number of Shares on the first anniversary of the Vesting Commencement Date and as to a further 6.25% on the expiry of 3 months from such anniversary and 6.25% on the expiry of
every subsequent period of 3 months until the Option is fully vested 4 years from the Vesting Commencement Date. 
  

	1.2	Words and expressions not otherwise defined herein have the same meaning they have in ITEPA. 

  

	1.3	Where the context so admits or requires words importing the singular shall include the plural and vice versa and words importing the masculine shall include the feminine. 

 

	1.4	Reference in the Rules of the Plan to any statutory provisions are to those provisions as amended, extended or re-enacted from time to time, and shall include any regulations made thereunder. The Interpretation Act 1978
shall apply to these Rules mutatis mutandis as if they were an Act of Parliament. 

  

	1.5	The headings in the rules of the Plan are for the sake of convenience only and should be ignored when construing the rules. 

  

	2.	Grant of Options 

  

	2.1	The Board may at any time grant Options at the Option Price to Eligible Employees nominated to it by the Committee. 

  

	2.2	The Board may at the Date of Grant impose such performance condition or performance conditions on the exercise of an Option as determined by the Committee. Such performance conditions: 

 

	 	(a)	must be objective and stated in writing at the Date of Grant; and 

  

	 	(b)	may not be waived, varied or amended by the Committee unless in accordance with the terms of such conditions or, where any waiver, variation or amendment is at the discretion of the Committee, it shall only be exercised
in a manner which the Committee has determined to be fair and reasonable and, if events happen which cause the Committee, acting fairly and reasonably, to consider that the waived, varied or amended condition would be appropriate and would result in
the waived, varied or amended condition being no easier and no more difficult to satisfy than the condition as it existed immediately prior to such waiver, variation or amendment. 

  
 5 

	2.3	The grant of an Option shall be subject to obtaining any approval or consent required under any applicable laws, regulations of governmental authority, and the requirements of the London Stock Exchange, AIM and any
other securities exchange on which the Shares are traded. 

  

	2.4	The Company shall issue to each Participant a duly executed certificate in respect of the Option in such form as the Board may from time to time prescribe. Such certificate must be sealed by the Company or executed as a
deed on behalf of the Company. No payment to the Company shall be required on the grant of an Option. 

  

	2.5	Subject to the rights of exercise by the Participant’s personal representatives pursuant to Rule 4.2, every Option shall be personal to the Participant to whom it is granted and shall not be transferable or in any
way alienable. 

  

	3.	Limit on value of Options 

  

	3.1	Any Option granted to an Eligible Employee shall be limited and take effect so that, immediately following such grant, the aggregate Market Value of all the Shares which he may acquire on the exercise in full of all
unexercised options then held by him under this Plan and any other share option Plan approved by HM Revenue & Customs under Schedule 4 and adopted by the Company or any Associated Company shall not exceed £30,000 (thirty thousand
pounds) or such other amount as shall from time to time be specified in paragraph 6(1) of Schedule 4. 

  

	3.2	In determining the limits in Rule 3.1 above, no account shall be taken of any Shares where the right to acquire them was released without being exercised within 30 days of its grant. 

 

	4.	Rights of Exercise and lapse of Options 

  

	4.1	An Option: 

  

	 	(a)	save as provided in Rules 4.2, 4.3, 4.4 and Rule 6 below shall not be exercised earlier than the fourth anniversary of the Vesting Commencement Date; 

 

	 	(b)	save as provided in Rule 4.2, 4.3 and Rule 6 below, may only be exercised by a Participant whilst he is a director or employee of a Constituent Company or an Associated Company; 

 

	 	(c)	may only be exercised if any performance conditions (as waived, varied or amended) imposed pursuant to Rule 2.2 have been fulfilled to the satisfaction of the Board, on the recommendation of the Committee;

  

	 	(d)	may not be exercised at any time when a Participant has or has had within the preceding 12 months a Material Interest in a Close Company which is: 

 

	 	(i)	the Company; or 

  

	 	(ii)	any company which has Control of the Company or is a Member of a Consortium which owns the Company. 

  
 6 

 Death of Participant 

 

	4.2	An Option may be exercised in the period of 12 months following the date of death of a Participant by the Participant’s personal representatives 

 

	 	(i)	to the extent that the Option has vested in accordance with the Vesting Schedule as at the Date of Death: and 

  

	 	(ii)	if any performance conditions (as waived, varied or amended) imposed pursuant to Rule 2.2 have been fulfilled to the satisfaction of the Board, on the recommendation of the Committee as at the Date of Death.

 To the extent that the Option is unvested in accordance with the Vesting Schedule as at the Date of Death, the Committee
shall have the discretion to permit the exercise of such unvested part of the Option within 12 months of the Date of Death. Such discretion shall only be exercised in a manner which the Committee has determined to be fair and reasonable. 

Participant leaving office or employment 
  

	4.3	If a Participant ceases to hold an office or employment with a Constituent Company or an Associated Company as a result of: 

  

	 	(a)	injury or disability; 

  

	 	(b)	redundancy within the meaning of the Employment Rights Act 1996; 

  

	 	(c)	Retirement; 

  

	 	(d)	early retirement by agreement with his employer; 

  

	 	(e)	the company which employs him ceasing to be under the Control of the Company or such company ceasing to be a Constituent Company; 

  

	 	(f)	the transfer or sale of the undertaking or part-undertaking in which he is employed to a person who is neither under the Control of the Company nor a Constituent Company; or 

 

	 	(g)	any other reason, at the discretion of the Board, acting fairly and reasonably, on the recommendation of the Committee. 

an Option may only be exercised within the period of six months following the Date of Cessation: 

 

	 	(i)	to the extent that the Option has vested in accordance with the Vesting Schedule as at the Date of Cessation: and 

  

	 	(ii)	if any performance conditions (as waived, varied or amended) imposed pursuant to Rule 2.2 have been fulfilled to the satisfaction of the Board, on the recommendation of the Committee as at the Date of Cessation.

 To the extent that the Option is unvested in accordance with the Vesting Schedule as at the Date of Cessation, the Committee
shall have the discretion exercisable before the Date of Cessation to permit the exercise of such unvested part of the Option within six months of the Date of Cessation. Such discretion shall only be exercised in a manner which the Committee has
determined to be fair and reasonable. 
 Admission to Main Market of London Stock Exchange, AIM or any other securities exchange
– for Options granted before 13 May 2014 only 

  
 7 

	4.4	Rule 4.4 shall only apply to Options granted before 13 May 2014 only. If the Company’s shares are admitted to listing on the Main Market of the London Stock Exchange, AIM or any other securities exchange, the
Option shall Vest in full immediately after the admission date (notwithstanding that part of the Option may be Unvested). The Option will be exercisable (subject to the discretion of the Board to permit an earlier exercise) as follows:

  

	 	(a)	25% immediately following the admission date; 

  

	 	(b)	a further 50% on the first anniversary of the admission date; 

  

	 	(c)	a further 25% on the second anniversary of the admission date. 

 Admission to Main Market
of London Stock Exchange, AIM or any other securities exchange – for Options granted on or after 13 May 2014 
  

	4.5	For the avoidance of doubt, Rule 4.4 shall not apply to all Options granted on or after 13 May 2014 and on admission vesting shall continue as detailed in the Vesting Schedule. 

 

	5.	Lapse of Options 

  

	5.1	Options shall lapse under the occurrence of the earliest of the following events: 

  

	 	(a)	the tenth anniversary of the Date of Grant; 

  

	 	(b)	the expiry of any of the periods specified in Rule 4.2 and 4.3 (save that if at the time any of the applicable periods under Rule 4.3 expire, time is running under the period in Rule 4.2, the Option shall not lapse by
reason of this Rule 4.4 until the expiry of the period under Rule 4.2); 

  

	 	(c)	the expiry of any of the periods specified in Rules 6.1, 6.5, 6.6 and 6.7 save where an option is released in consideration of the grant of a New Option (during one of the periods specified in Rules 6.1(a), 6.5 or 6.6)
pursuant to Rule 7.1; 

  

	 	(d)	The Participant ceasing to hold an office or employment with a Constituent Company or an Associated Company in any circumstances other than: 

 

	 	(i)	where the cessation of office or employment arises on any of the grounds specified in Rules 4.2 or 4.3; or 

  

	 	(ii)	where the cessation of employment arises on any ground whatsoever during any of the periods specified in Rule 6; 

  

	 	(e)	subject to Rule 6.7 the passing of an effective resolution, or the making of an order by the Court, for the winding-up of the Company; 

 

	 	(f)	the Participant being deprived of the legal or beneficial ownership of the Option by the operation of the law, or doing or omitting to do anything which causes him to be so deprived or being declared bankrupt.

  

	6.	Takeover, Reconstruction, Winding-Up and Listing 

 Change of Control 

  
 8 

	6.1	If any person obtains Control of the Company as a result of 

  

	 	(a)	making a general offer to acquire the whole of the issued share capital of the Company which is either unconditional or is made on a condition such that if it is satisfied the person making the offer will have control
of the Company, 

  

	 	(b)	negotiating a share sale and purchase agreement with the shareholders of the Company which contemplates that the person will obtain Control of the Company on completion; 

an Option may only be exercised to the extent set out in Rule 6.2 and 6.3 within the period of six months of the time when the person obtains
Control of the Company (the “Unconditional Time”) or immediately before the Unconditional Time. 
  

	6.2	An Option may be exercised under Rule 6.1: 

  

	 	(a)	to the extent that the Option has vested in accordance with the Vesting Schedule as at the Unconditional Time: and 

  

	 	(b)	if any performance conditions (as waived, varied or amended) imposed pursuant to Rule 2.2 have been fulfilled to the satisfaction of the Board, on the recommendation of the Committee as at the Unconditional Time.

  

	6.3	An Option may be exercised under Rule 6.1: 

  

	 	(a)	to the extent of 75% of the unvested part of the Option in accordance with the Vesting Schedule as at the Unconditional Time; and 

  

	 	(b)	the Committee shall have the discretion to permit the exercise of the remaining 25% of the unvested part of the Option. Such discretion shall only be exercised in a manner which the Committee has determined to be fair
and reasonable. 

  

	6.4	For the purpose of Rule 6.1 a person shall be deemed to have obtained Control of the Company if he and others acting in concert (as defined by the City Code on Take-overs and Mergers) with him have together obtained
Control of it. 

 Compulsory acquisition or squeeze out 

 

	6.5	If any person becomes bound or entitled to acquire Shares under Sections 979 to 982 of the Companies Act 2006 an Option may be exercised at any time when that person remains so bound or entitled (to the extent set out
in Rule 6.2 and 6.3). 

 Scheme of arrangement or compromise 

 

	6.6	If under Section 899 of the Companies Act 2006 it is proposed that the Court sanctions a compromise or arrangement proposed for the purposes of or in connection with a Plan for the reconstruction of the Company or
its amalgamation with any other company or companies: 

  

	 	(a)	The Company shall give notice thereof to all Participants at the same time as it sends notices to members of the Company calling the meeting to consider such a compromise or arrangement. 

 

	 	(b)	The Participant may then exercise the Option subject to the terms of this Rule before the later of the expiry of six months from the date of such notice and the date on which the Court sanctions the compromise or
arrangement and thereafter the Option shall lapse conditionally on such compromise or arrangement being sanctioned by the Court and becoming effective. 

  
 9 

	 	(c)	The exercise of the Option shall be to the extent set out in Rule 6.2 and 6.3 (provided that the Unconditional Time shall be defined as the date of the Court sanctioning the compromise or arrangement) 

 

	 	(d)	The exercise of an Option under this sub-rule shall be conditional on such compromise or arrangement being sanctioned by the Court and becoming effective. 

Voluntary winding-up 
  

	6.7	If notice is duly given of a resolution for the voluntary winding-up of the Company, the Company shall give notice thereof to all Participants and thereafter an Option may be exercised until the resolution is duly
passed or defeated or the meeting concluded or adjourned sine die provided that any such exercise of an Option pursuant to this sub-rule shall be conditional upon the said resolution being duly passed and shall only be in respect of the part of the
Option vested as at the date of the resolution. If such resolution is duly passed all Options shall, to the extent that they have not been exercised, lapse immediately. 

 

	7.	Replacement Options 

  

	7.1	If Options become exercisable pursuant to any of Rule 6.1 (a) (where the person acquiring control is a company), 6.5 and 6.6 above, any Participant may at any time within the Appropriate Period, by agreement with
the acquiring company, release any Option which has not lapsed (“the Old Option”) in consideration of the grant to him of an Option (“the New Option”) which (for the purpose of Part 6 of Schedule 4) is equivalent to the Old
Option but relates to shares in a different company (whether the company which has obtained Control of the Company itself or some other company falling within paragraph 16(b) or (c) of Schedule 4) provided always that, where Options are
conditionally exercisable under Rule 6.6 above, such release and grant shall be made subject to the same conditions and so as to become effective on satisfaction of the conditions which are (or would be) applicable to exercise. 

 

	7.2	The New Option shall not be regarded for the purposes of Rule 7.1 as equivalent to the Old Option unless the conditions set out in paragraph 27(4) of Schedule 4 are satisfied but so that the provisions of the Plan shall
for this purpose be construed as if: 

  

	 	(a)	the New Option were an option granted under the Plan at the same time as the Old Option; 

  

	 	(b)	except for the purpose of the definition of “Constituent Company” in Rule 1, the reference to Mimecast Limited in the definition of “the Company” in Rule 1 were a reference to the different company
mentioned in Rule 7.1, however the Plan will remain that of Mimecast Limited; and 

  

	 	(c)	all conditions imposed by Rule 2.2 have been satisfied. 

  

	8.	Manner of Exercise 

  

	8.1	An Option may be exercised in whole or in part. 

  

	8.2	 Subject to Rule 8.3, an Option may be exercised by the delivery to the Company Secretary or his duly appointed agent of a certificate covering at
least all the Shares over which the Option is then to be exercised, with the notice of exercise in the prescribed form duly completed and signed by the Participant together with a remittance for the Exercise Price payable in respect of the Shares
over which the 

  
 10 

	 	
Option is to be exercised. If any conditions must be fulfilled before an Option may be exercised, the delivery of the certificate shall not be treated as effecting the exercise of an Option
unless and until the Board is satisfied that the conditions have been fulfilled. 

  

	8.3	In the event that any PAYE Liability becomes due on the exercise of an Option, the Option may not be exercised unless: 

  

	 	(a)	the Constituent Company is able to deduct an amount equal to the whole of the PAYE Liability from the Participant’s net pay for the next pay period; or 

 

	 	(b)	the Participant has paid to the Constituent Company an amount equal to the PAYE Liability; or 

  

	 	(c)	the sum of the amount that the Participant has paid to the Constituent Company in respect of the Constituent Company’s obligation to satisfy the PAYE liability and the total amount that the Constituent Company is
able to deduct from the Participant’s net pay for the next pay period is equal to or more than the PAYE Liability (for the avoidance of doubt any overdeduction of the PAYE Liability shall be reimbursed to the Participant as soon as is
practicable by cheque or through the Participant’s pay); or 

  

	 	(d)	the Participant has given irrevocable instructions to the Company’s brokers (or any other person acceptable to the Company) for the sale of sufficient shares acquired on the exercise of the Option to realise an
amount equal to the PAYE Liability and the payment of the PAYE Liability to the Company 

  

	9.	Issue or Transfer of Shares 

  

	9.1	Subject to Rule 9.3, Shares to be issued pursuant to the exercise of an Option shall be allotted to the Participant (or his nominee) within 28 days following the date of effective exercise of the Option.

  

	9.2	Subject to Rule 9.3, the Board shall procure the transfer of any Shares to be transferred to a Participant (or his nominee) pursuant to the exercise of an Option within 28 days following the date of effective exercise
of the Option. 

  

	9.3	The allotment or transfer of any Shares under the Plan shall be subject to obtaining any such approval or consent as is mentioned in Rule 2.3 above. 

 

	9.4	Shares issued pursuant to the Plan will rank pari passu in all respects with the Shares then in issue, except that they shall not rank for any right attaching to Shares by reference to a record date preceding the date
of exercise. 

  

	9.5	Shares transferred pursuant to the Plan shall not be entitled to any rights attaching to Shares by reference to a record date preceding the date of exercise. 

 

	9.6	If and so long as the Shares are listed on the London Stock Exchange, AIM or on any other securities exchange, the Company shall apply for listing of any Shares pursuant to the Plan as soon as practicable after the
allotment thereof. 

  

	10.	Adjustments 

  

	10.1	 The number of Shares over which an Option is granted and the Option Price therefore (and where an Option has been exercised but no Shares have been
allotted or transferred pursuant to such exercise, the number of Shares which may be so allotted or transferred and the price at which they may be acquired) shall be adjusted in such

  
 11 

	 	
manner as the Board shall determine following any capitalisation issue, any offer or invitation made by way of rights, subdivision, consolidation, reduction or other variation in the share
capital of the Company, to the intent that (as nearly as may be without involving fractions of a Share or an Option Price calculated to more than two decimal places) the aggregate Exercise Price payable in respect of an Option shall remain
unchanged, provided that no adjustment made pursuant to this Rule 10.1 shall be made without the prior approval of HM Revenue & Customs (so long as the Plan is approved by HM Revenue & Customs). 

 

	10.2	Apart from pursuant to this Rule 10.2, no adjustment under Rule 10.1 above may have the effect of reducing the Option Price to less than the nominal value of a Share. Where an Option subsists over both issued and
unissued Shares any such adjustment may only be made if the reduction of the Option Price of Options over both issued and unissued Shares can be made to the same extent. Any adjustment made to the Option Price of Options over unissued Shares shall
only be made if and to the extent that the Board shall be authorised to capitalise from the reserves of the Company a sum equal to the amount by which the nominal value of the Shares in respect of which the Option is exercisable exceeds the adjusted
Exercise Price and to apply such sum in paying up such amount on such Shares so that on exercise of any Option in respect of which such a reduction shall have been made the Board shall capitalise such sum (if any) and apply the same in paying up
such amount as aforesaid. 

  

	10.3	The Board may take such steps as it may consider necessary to notify Participants of any adjustment made under this Rule 10 and to call in, cancel, endorse, issue or reissue any certificate consequent upon such
adjustment. 

  

	11.	Administration 

  

	11.1	Any notice or other communication under or in connection with the Plan may be given by personal delivery or by sending the same by post, in the case of a company to its registered office, and in the case of an
individual to his last known address, or, where he is a director or employee of a Constituent Company or an Associated Company, either to his last known address or to the address of the place of business at which he performs the whole or
substantially the whole of the duties of his office or employment, and where a notice or other communication is given by first-class post, it shall be deemed to have been received 72 hours after it was put into the post properly addressed and
stamped. 

  

	11.2	The Company may distribute to Participants copies of any notice or document normally sent by the Company to the holders of Shares. 

  

	11.3	In the case of partial exercise of an Option, the Board may in consequence call in, endorse, cancel and reissue, as it considers appropriate, any certificate for the balance of the Shares over which the Option was
granted. 

  

	11.4	If any certificate shall be worn out, defaced or lost, it may be replaced on such evidence being provided as the Board may require. 

  

	11.5	The Company shall at all times keep available for allotment unissued Shares at least sufficient to satisfy all Options under which Shares may be subscribed or procure that sufficient Shares are available for transfer to
satisfy all Options under which Shares may be acquired. 

  

	11.6	 The Plan shall be administered by the Committee. The Committee shall have full authority, consistent with the Plan, to administer the Plan, including
authority to interpret and construe any provision of the Plan and to adopt such regulations for 

  
 12 

	 	
administering the Plan and such forms of exercise as it may deem necessary or appropriate. Decisions of the Committee shall be final and binding on all parties. 

 

	11.7	The cost of introducing and administering the Plan shall be borne by the Company. 

  

	12.	Alterations 

  

	12.1	Subject to Rules 12.2, 12.4 and 12.5, the Board may at any time alter or add to all or any of the provisions of the Plan in any respect. 

 

	12.2	No alteration or addition shall be made under Rule 12.1 which would abrogate or adversely affect the subsisting rights of a Participant unless it is made: 

 

	 	(a)	with the consent in writing of such number of Participants as hold Options under the Plan to acquire 75 per cent, of the Shares which would be issued or transferred if all Options granted and subsisting under the
Plan were exercised; or 

  

	 	(b)	by a resolution at a meeting of Participants passed by not less than 75 per cent of the Participants who attend and vote either in person or by proxy; and 

for the purpose of this Rule 12.2 the provisions of the Articles of Association of the Company relating to shareholder meeting shall apply
mutates mutandis. 
  

	12.3	As soon as reasonably practicable after making any alteration or addition under Rule 12.1, the Board shall give written notice thereof to any Participant affected thereby. 

 

	12.4	No alteration shall be made to the Plan if following the alteration the Plan would cease to be an Employees’ Share Scheme. 

  

	12.5	If an alteration or addition is made under Rule 12.1 at a time when the Plan is approved by HM Revenue & Customs under Schedule 4 and amounts to an alteration to a key feature of the Plan (being a provision of
the Plan which is necessary in order to meet the requirements of Schedule 4), it shall not have effect until it has been approved by HM Revenue & Customs. 

 

	13.	General 

  

	13.1	The Company and any Subsidiary of the Company may provide money to the trustees of any trust or any other person to enable them or him to acquire Shares to be held for the purposes of the Plan, or enter into any
guarantee or indemnity for those purposes. In addition, the Company may require any Subsidiary to enter into such other agreement or agreements as it shall deem necessary to oblige such Subsidiary to reimburse the Company for any other amounts paid
by the Company hereunder, directly or indirectly in respect of such Subsidiary’s employees. Nothing in the Plan shall be deemed to give any employee of any Constituent Company any right to participate in the Plan. 

 

	13.2	The rights and obligations of any individual under the terms of his office or employment with a Constituent Company shall not be affected by his participation in the Plan or any right which he may have to participate
therein, and an individual who participates therein shall waive all and any rights to compensation or damages in consequence of the termination of his office or employment with a Constituent Company for any reason whatsoever insofar as those rights
arise or may arise from his ceasing to have rights under or be entitled to exercise any Option under the Plan as a result of such termination or from the loss or diminution in value of such rights or entitlements. 

  
 13 

	13.3	All Participants and Eligible Employees agree as a condition of their participation in the Plan that any personal data in relation to them may be held by any company in the Group or passed to any third party in
connection with the administration of the Plan. 

  

	13.4	These Rules shall be governed by and construed in accordance with the law of England. 

  
 14 

 Certificate No. 

MIMECAST LIMITED 

EXECUTIVE SHARE OPTION SCHEME 

OPTION CERTIFICATE – FOR APPROVED OPTION 

This is to certify that [Name] of [Address] is the holder of an Option to acquire up to a maximum of
[            ] shares of [            ] each in Mimecast Limited at a price of
[            ] per B Ordinary Share. 
 This Option was granted on [date] under the Rules
of the Mimecast Limited Approved Share Option Plan (the “Plan Rules”). 
 The Option is exercisable in accordance with the Plan Rules. [The
exercise of the Option is subject to the satisfaction of the performance condition set out in the attached schedule.] The Option may not be exercised after 10 years from the date of grant. 

A condition of the exercise of the Option is that the holder of the Option agrees to pay any secondary Class 1 NIC (Employer’s NIC) arising on such
exercise. 
 This Option is not transferable and will lapse upon the occasion of an assignment, charge, disposal or other dealing with the rights conveyed
by it. 
  

					
	SIGNED as a Deed	  		  	
	by Mimecast Limited	  	)	  	
	acting by	  	)	  	

  

			
		 	Director
		
		 	Director/Secretary
		
	DATED:        	 	  

 THIS CERTIFICATE IS IMPORTANT AND SHOULD BE 

KEPT IN A SAFE PLACE

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