Exhibit 10.4

PATENT SECURITY AGREEMENT

This PATENT SECURITY AGREEMENT (this “Agreement”), dated as of July 23, 2018, is
made by MIMECAST SERVICES LIMITED, a private company incorporated in England and
Wales with registration number 4901524, (the “Grantor”), in favor of JPMORGAN
CHASE BANK, N.A., in its capacity as administrative agent for the Lenders party
to the Credit Agreement referred to below (in such capacity, the “Administrative
Agent”).

W I T N E S S E T H:

WHEREAS, pursuant to that certain Credit Agreement dated as of the date hereof
(as amended, restated, amended and restated, supplemented or otherwise modified
from time to time, the “Credit Agreement”), by and among MIMECAST LIMITED, a
public company incorporated in Jersey with registration number 119119, as
borrower, certain of its subsidiaries from time to time party thereto, as
guarantors, the lenders from time to time party thereto (the “Lenders”) and the
Administrative Agent, the Lenders have agreed to extend credit and make certain
financial accommodations to the Grantor;

WHEREAS, in connection with the Credit Agreement, the Grantor, the other Loan
Parties (as defined in the Credit Agreement) and the Administrative Agent have
entered into that certain Pledge and Security Agreement dated as of the date
hereof (as amended, restated, amended and restated, supplemented or otherwise
modified from time to time, the “Security Agreement”); and that certain English
law Security Agreement dated as the date hereof (as amended, restated, amended
and restated, supplemented or otherwise modified from time to time, the “UK
Debenture”, and together with the Security Agreement being, the “Collateral
Agreements”); and

WHEREAS, pursuant to the Credit Agreement and the Collateral Agreements, the
Grantor is required to execute and deliver to the Administrative Agent this
Agreement;

NOW, THEREFORE, in consideration of the premises and mutual covenants herein
contained and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the Grantor hereby agrees as
follows:

1.    DEFINED TERMS. All capitalized terms used but not otherwise defined herein
have the meanings given to them in the Security Agreement.

2.    GRANT OF SECURITY INTEREST IN PATENT COLLATERAL. The Grantor hereby
pledges, assigns and grants to the Administrative Agent, on behalf of and for
the ratable benefit of the Secured Parties, a continuing first priority security
interest in all of the Grantor’s right, title and interest in, to and under the
following, whether presently existing or hereafter created or acquired
(collectively, the “Patent Collateral”):

2.1.    all of its Patents, including those referred to on Schedule I hereto;

2.2.    all reissues, divisions, continuations, continuations-in-part, renewals,
extensions and reexaminations of and amendments to the foregoing;

2.3.    all rights of any kind whatsoever of the Grantor accruing under any of
the foregoing provided by applicable law of any jurisdiction, by international
treaties and conventions and otherwise throughout the world;

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2.4.    any and all royalties, fees, income, payments, products and other
proceeds now or hereafter due or payable with respect to any and all of the
foregoing; and

2.5.    any and all claims and causes of action with respect to any of the
foregoing, whether occurring before, on or after the date hereof, including all
rights to and claims for damages, restitution and injunctive and other legal and
equitable relief for past, present and future infringement, misappropriation,
violation, misuse, breach or default, with the right but no obligation to sue
for such legal and equitable relief and to collect, or otherwise recover, any
such damages.

3.    COLLATERAL AGREEMENTS. The security interests granted pursuant to this
Agreement are granted in conjunction with the security interests granted to the
Administrative Agent pursuant to the Collateral Agreements. The Grantor hereby
acknowledges and affirms that the rights and remedies of the Administrative
Agent with respect to the security interest in the Patent Collateral made and
granted hereby are more fully set forth in the Collateral Agreements, the terms
and provisions of which are incorporated by reference herein as if fully set
forth herein. In the event of a conflict between the provisions of this
Agreement and the Security Agreement or the UK Debenture, the Security Agreement
or UK Debenture shall control, as applicable. This Agreement shall constitute a
Collateral Document and a Loan Document (as such terms are defined in the Credit
Agreement).

4.    AMENDMENTS IN WRITING. None of the terms or provisions of this Agreement
may be waived, amended, supplemented or otherwise modified except by an
instrument in writing signed by the Administrative Agent and the Grantor.

5.    GOVERNING LAW. This Agreement and the rights and obligations of the
parties hereto shall be governed by, and construed in accordance with, the laws
of the State of New York.

6.    COUNTERPARTS. This Agreement may be executed in any number of counterparts
and by the different parties hereto on separate counterparts and each such
counterpart shall be deemed to be an original, but all such counterparts shall
together constitute but one and the same Agreement. Receipt by telecopy or other
electronic transmission (including “PDF”) of any executed signature page to this
Agreement shall constitute effective delivery of such signature page.

[Remainder of this page intentionally left blank]

 

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IN WITNESS WHEREOF, the Grantor has caused this Agreement to be executed and
delivered by its duly authorized officer as of the date first set forth above.

 

GRANTOR: MIMECAST SERVICES LIMITED By:  

/s/ Peter Andrew James Campbell

 

Peter Andrew James Campbell

Executive Director

 

[Signature Page to U.S. Patent Security Agreement]

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ADMINISTRATIVE AGENT: JPMORGAN CHASE BANK, N.A. By:  

/s/ Eleftherios Karsos

 

Eleftherios Karsos

Authorized Signatory

 

[Signature Page to U.S. Patent Security Agreement]

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SCHEDULE I

to

PATENT SECURITY AGREEMENT

PATENT REGISTRATIONS:

 

Owner

  

Title

   App. No.      Filing Date      Pat. No.      Issue Date  

Mimecast Services Ltd. (UK)

   Reducing Latency in Performing a Task Among Distributed Systems     
12/964,219        12/9/2010        9,274,862        3/1/2016  

Mimecast Services Ltd. (UK)

   Enhancing Communication      13/044,842        3/10/2011        9,294,308  
     3/22/2016  

Mimecast Services Ltd. (UK)

   Enhancing Communication      15/052,044        2/24/2016        9,634,974  
     4/25/2017  

Mimecast Services Ltd. (UK)

   Analyzing Stored Electronic Communications      13/273,696        10/14/2011
       9,009,220        4/14/2015  

Mimecast Services Ltd. (UK)

   Analyzing Stored Electronic Communications      14/636,308        3/3/2015  
     9,686,163        6/20/2017  

Mimecast Services Ltd. (UK)

   Associative Search Systems and Methods      14/021,391        9/9/2013       
9,846,740        12/19/2017  

Mimecast Services Ltd. (UK)

  

Facilitating User

Communication About a Common Topic

     14/025,903        9/13/2013        9,432,419        8/30/2016  

Mimecast Services Ltd. (UK)

   Facilitating User Communication About a Common Topic      15/090,652       
4/5/2016        9,838,446        12/5/2017  

Mimecast Services Ltd. (UK)

   Automatic Translator Identification      14/447,683        7/31/2014       
9,444,773        9/13/2016  

Mimecast Services Ltd. (UK)

   System for Annotation of Electronic Messages with Contextual Information     
14/813,034        7/29/2015        9,628,419        4/18/2017  

Mimecast Services Ltd. (UK)

   Electronic Message Threat Protection System for Authorized Users     
14/855,200        9/15/2015        9,467,435        10/11/2016  

Mimecast Services Ltd. (UK)

   Malware Detection System Based on Stored Data      15/010,023       
1/29/2016        9,654,492        5/16/2017  

PATENT APPLICATIONS:

 

Owner

  

Title

   App. No.      Filing Date  

Mimecast Services Ltd. (UK)

   Reducing Latency in Performing a Task Among Distributed Systems     
15/055,674        2/29/2016  

Mimecast Services Ltd. (UK)

   Analyzing Stored Electronic Communications      15/625,461        6/16/2017  

Mimecast Services Ltd. (UK)

   Encoding Data in Email Headers      13/950,785        7/27/2013  

Mimecast Services Ltd. (UK)

   Sharing Artifacts in Permission- Protected Archives      14/024,297       
9/11/2013  

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Owner

  

Title

   App. No.      Filing Date  

Mimecast Services Ltd. (UK)

   Facilitating User Communication About a Common Topic      15/830,606       
12/4/2017  

Mimecast Services Ltd. (UK)

   Displaying Messages Relevant to System Administration      14/134,099       
12/19/2013  

Mimecast Services Ltd. (UK)

   System for Annotation of Electronic Messages with Contextual Information     

15/489,198

(Continuation
of App. No.

14/813,034

 

 
 

) 

     4/17/2017  

Mimecast Services Ltd. (UK)

   Mediated Access to Resources      15/449,569        3/3/2017  

Mimecast Services Ltd. (UK)

   User Login Credential Warning System      15/461,857        3/17/2017  

Mimecast Services Ltd. (UK)

   Malware Detection System Based on Stored Data      15/592,543       
5/11/2017  

Mimecast Services Ltd. (UK)

   Method and System for Detecting Domain Impersonation Using Network Metadata
     62/581,860        11/6/2017  

Mimecast Services Ltd. (UK)

   Analyze on Hover: A Method of Proactive Analysis of Files, Links, and
Attachments      62/613,189        1/3/2018  

Mimecast Services Ltd. (UK)

   Representing Content to Minimize Accidental Harm by Users      62/657,115  
     4/13/2018  

Mimecast Services Ltd. (UK)

   Representing Content to Minimize Accidental Harm by Users      62/665,709  
     5/2/2018  

Mimecast Services Ltd. (UK)

   Identifying Similar People from Communication Archives      62/657,117       
4/13/2018  

Mimecast Services Ltd. (UK)

   Alerting Synchronous Callers to Time Zone      62/688,616        6/22/2018  

Mimecast Services Ltd. (UK)

   Usable Authentication By Prompted Voice      62/690,088        6/26/2018  

 

[Signature Page to U.S. Patent Security Agreement]