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Exhibit 10.19 ZIX CORPORATION
STOCK OPTION AGREEMENT THIS STOCK OPTION AGREEMENT (Agreement) is made and entered into as of the date set forth on
the signature page attached hereto (the Signature Page) with respect to the stock options granted
by Zix Corporation, a Texas corporation (the Company), to the Optionee (Optionee) listed on the
signature page hereto. WHEREAS, the Company wishes to recognize the contributions of the Optionee to the Company and
to encourage the Optionees sense of proprietorship in the Company by owning the Common Stock, par
value $.01 per share (the Common Stock), of the Company; NOW, THEREFORE, in consideration of the mutual agreements and covenants contained herein, the
Company hereby grants to the Optionee a non-qualified stock option (Option) to purchase up to the
total number of shares of the Common Stock set forth on the Signature Page at the price per share
(the Option Price) as set forth on the Signature Page on the terms and conditions and subject to
the restrictions as set forth in this Agreement and the provisions of the applicable Zix
Corporation stock option plan (which is incorporated herein by reference) (the Plan), which is
referenced on the Signature Page. All defined terms contained herein shall have the meanings
ascribed to them in the Plan, except as otherwise provided herein. 1. Definitions. a. Acceleration Option Event. An Acceleration Option Event shall have occurred if
at any time during the stated term (as defined in Paragraph 2 below) any of the following events
shall occur: (i) Any Sale of the Company or any Material Subsidiary; or (ii) Any Acquiring Person has become the beneficial owner of securities which, when
added to any securities already owned by such person, would represent in the aggregate 35%
or more of the then-outstanding securities of the Company that are entitled to vote to
elect any class of directors; (iii) If, at any time, the Continuing Directors then serving on the Board cease for
any reason to constitute at least a majority thereof; (iv) Any occurrence that would be required to be reported in response to Item 6(e) of
Schedule 14A of Regulation 14A or any successor rule or regulation promulgated under the
Exchange Act;




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(v) If the person that holds the position of Chief Executive Officer (of the Company)
as of the date of this Agreement ceases to hold the position of Chief Executive Officer (of
the Company) and thereafter there is any material diminution in Optionees duties that is
not cured within thirty days after notice of such noncompliance has been given (within 30
days of the alleged material diminution) by Optionee to the Company. A change in duties
will not be considered to be a material diminution in duties if, after such change,
Optionee is an officer of the Company; Optionees reporting relationship does not change or
Optionee reports to the Companys Chief Executive Officer or Chief Operating Officer; and a
substantial portion of Employees duties are in Employees field of professional training
or experience. b. Affiliate and Associate. Affiliate and Associate shall have the respective
meanings ascribed to such terms in Rule 12b-2 of the General Rules and Regulations under the
Exchange Act in effect on the date of this Agreement. c. Continuing Director. A Continuing Director shall mean a director of the Company
who (i) is not an Acquiring Person or an Affiliate or Associate thereof, or a representative of an
Acquiring Person or nominated for election by an Acquiring Person, and (ii) was either a member of
the Board on the date of this Agreement or subsequently became a director of the Company and whose
initial election or initial nomination for election by the Companys shareholders was approved by a
majority of the Continuing Directors then on the Board. d. Exchange Act. Exchange Act shall mean the Securities Exchange Act of 1934, as
amended, and the rules and regulations promulgated thereunder. e. Disability. Disability shall mean any medically determinable physical or mental
impairment that, in the opinion of the Committee, based upon medical reports and other evidence
satisfactory to the Committee, can reasonably be expected to prevent the Optionee from performing
substantially all of his or her customary duties of employment (with or without reasonable
accommodation) for a continuous period of not less than 12 months. f. Material Subsidiary. A Material Subsidiary shall mean any majority-owned
subsidiary of the Company that is material to the business of the Company, taken as a whole. g. Resignation. Resignation shall mean the voluntary termination by the Optionee of
his or her employment relationship with the employing Subsidiary and, if applicable, Company under
circumstances other than voluntary Retirement. h. Retirement. Retirement shall mean the termination of Optionees employment in
accordance with the requirements of a written retirement plan, policy or
rule of the Company that has been duly adopted by the Company or employing Subsidiary, as
applicable.




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i. Sale. A Sale occurs with respect to the Company or a Material Subsidiary, as
applicable, if it engages in a merger, consolidation, recapitalization, reorganization, or sale,
lease, license, transfer, or other effective disposition of all or substantially all of the
Companys or Material Subsidiarys assets and the Company or its shareholders or Affiliates
immediately before such transaction beneficially own, immediately after or as a result of such
transaction, equity securities of the surviving or acquiring corporation or such corporations
parent corporation possessing less than 51% of the voting power of the surviving or acquiring
person or such persons parent corporation, provided that a Sale shall not be deemed to occur upon
any public offering or series of such offerings of securities of the Company or a Material
Subsidiary that results in any such change in beneficial ownership. 2. Term of Option. The term of this Option shall expire on the expiration date set forth
in the Signature Page (the stated term), except as such term may be otherwise shortened by the
other provisions of the Plan or this Agreement. 3. Exercise of Option. a. Exercise. This Option shall become exercisable in increments as set forth in the
Signature Page. However, this Option shall become exercisable upon the occurrence of an
Acceleration Option Event as to all options that have not vested as of the occurrence of the
Acceleration Option Event. Except as provided in the Plan, the Option shall not be exercisable
unless Optionee shall, at the time of exercise, be an employee of the Company or a Subsidiary, and
once the Option has become exercisable with respect to a certain number of shares as provided
above, it shall thereafter be exercisable as to all of that number of shares, or as to any part
thereof, until expiration or termination of this Option. However, this Option may not be exercised
as to less than 100 shares at any one time (or the remaining shares then purchasable under this
Option, if less than 100 shares). b. Adjustment. In the event there is any adjustment to the Common Stock the Board of
Directors or Committee shall make such adjustment as it deems appropriate to the number of shares
subject to the Option or to the Option Price, or both. c. Method of Exercise. This Option may be exercised only by written notice (the
Exercise Notice) by the Optionee to the Company at its principal executive office. The Exercise
Notice shall be deemed given when deposited in the U. S. mails, postage prepaid, addressed to the
Company at its principal executive office, or if given other than by deposit in the U.S. mails,
when delivered in person to an officer of the Company at that office. The date of exercise of this
Option (the Exercise Date) shall be the date of the postmark if the notice is mailed or the date
received if the notice is delivered other than by mail. The Exercise Notice shall state the number
of shares in respect of which this Option is being exercised and, if the shares for which this
Option is being exercised are to




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be evidenced by more than one stock certificate, the denominations in which the stock certificates
are to be issued. The Exercise Notice shall be signed by the Optionee and shall include the
complete address of such person, together with such persons social security number. This Option may be exercised either by tendering cash in the amount of the Option Price or,
with the Companys consent, by tendering shares of Common Stock (which may include shares
previously acquired upon exercise of options granted under the Plan). The Exercise Notice shall be
accompanied by payment of the aggregate Option Price of the shares purchased by cash, a certified
cashiers check or, at the Companys option, by delivery of shares of Common Stock having a Fair
Market Value on the date immediately preceding the exercise date equal to the Option Price. If the shares to be purchased are covered by an effective registration statement under the
Securities Act of 1933, as amended, any option granted under the Plan may be exercised by a
broker-dealer acting on behalf of an Optionee if (a) the broker-dealer has received from the
Optionee or the Company a fully- and duly-endorsed agreement evidencing such option, together with
instructions signed by the Optionee requesting the Company to deliver the shares of Common Stock
subject to such option to the broker-dealer on behalf of the Optionee and specifying the account
into which such shares should be deposited, (b) adequate provision has been made with respect to
the payment of any withholding taxes due upon such exercise, and (c) the broker-dealer and the
Optionee have otherwise complied with Section 220.3(e)(4) of Regulation T, 12 CFR Part 220, or any
successor provision. The certificates for shares of Common Stock as to which this Option shall have been so
exercised shall be registered in the name of the Optionee and shall be delivered to the Optionee at
the address specified in the Exercise Notice. An option exercise shall be valid only if the
Optionee makes payment or other arrangements relating to the withholding tax obligations discussed
in Paragraph 8. In the event the person exercising this Option is a transferee of the Optionee by
will or under the laws of descent and distribution, the Exercise Notice shall be accompanied by
appropriate proof of the right of such transferee to exercise this Option. 4. Termination of Option. In the event Optionee ceases to be an employee of either the Company or a Subsidiary of the
Company due to death, Retirement, Resignation, Disability or termination of Optionees employment
by the Company for any reason other than Cause, as such term is defined in that certain Severance
Agreement between Optionee and Company, dated  (such five events each being a
Qualified Termination), this Option may be exercised by the Optionee or his or her estate,
personal representative or beneficiary to the fullest extent that the Optionee was entitled to
exercise the same on the day immediately prior to such termination (i) at any time within the
one-year period commencing on the day next following such termination if such




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termination is due to the occurrence of any Qualified Termination other than Resignation; or (ii)
at any time within the thirty-day period commencing on the day next following the effective date of
such termination if such termination is due to the Resignation of the Optionee (or in any such case
in (i) or (ii) above, if shorter, only for the remaining stated term of this Option). In the event
that the Optionees employment is terminated by the Company for Cause, as such term is defined in
that certain Severance Agreement between Optionee and Company, dated , this Option
shall automatically expire simultaneously with such termination of employment. After the Optionees death, this Option shall be exercisable only by the executor or
administrator of the Optionees estate, or if the Optionees estate is not in administration, by
the person or persons to whom the Optionees rights shall have passed by the Optionees will or
under the laws of descent and distribution of the state where the Optionee was domiciled at the
date of death. 5. No Rights as Shareholder.Neither the Optionee nor any person claiming under or through
the Optionee shall be or have any rights or privileges of a shareholder of the Company in respect
of any of the shares issuable upon the exercise of this Option, unless and until certificates
representing such shares shall have been issued (as evidenced by the appropriate entry on the books
of the Company or of a duly authorized transfer agent of the Company). 6. State and Federal Securities Regulation.No shares shall be issued by the Company upon
the exercise of this Option unless and until any then-applicable requirements of state and federal
laws and regulatory agencies shall have been fully complied with to the satisfaction of the Company
and its counsel. The Company may suspend for a reasonable period or periods the time during which
this Option may be exercised if, in the opinion of the Company, such suspension is required to
enable the Company to remain in compliance with regulatory requirements relating to the issuance of
shares of Common Stock subject to this Option. This Option is subject to the requirement that, if
at any time the Company shall determine, in its discretion, that the listing, registration or
qualification of the shares of common stock subject to this Option upon any securities exchange or
under any state or federal law, or the consent or approval of any government regulatory body, is
necessary or desirable as a condition of, or in connection with, the granting or exercise of this
Option or the issue or purchase of shares under this Option, this Option may not be exercised in
whole or in part until such listing, registration, qualification, consent or approval shall have
been effected or obtained free of any conditions not acceptable to the Company. The Company shall
be under no obligation to effect or obtain any such listing, registration, qualification, consent
or approval if the Company shall determine, in its discretion, that such action would not be in the
best interest of the Company. The Company shall not be liable for damages due to a delay in the
delivery or issuance of any stock certificates for any reason whatsoever, including, but not
limited to, a delay caused by listing, registration or qualification of the shares of Common Stock
subject to an option upon any securities exchange or under any federal or state law or the
effecting or obtaining of any consent or approval of any governmental body with respect to the granting or exercise of this Option or the issue or purchase
of shares under this Option.




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7. Modification of Options.At any time and from time-to-time the Committee may execute an
instrument providing for modification, extension, or renewal of any outstanding option, provided
that no such modification, extension or renewal shall impair this Option in any respect without the
written consent of the holder of this Option. 8. Withholding of Taxes.The Company may make such provisions and take such steps as it
may deem necessary or appropriate for the withholding of any taxes which the Company or any
Subsidiary is required by any law or regulation of any governmental authority, whether federal,
state or local, domestic or foreign, to withhold in connection with any option, including, but not
limited to, the withholding of the issuance of all or any portion of the shares of Common Stock
subject to this Option until the Optionee reimburses the Company or the applicable Subsidiary for
the amount the Company or the applicable Subsidiary is required to withhold with respect to such
taxes, canceling any portion of the issuance in an amount sufficient to reimburse the Company or
the applicable Subsidiary for the amount it is required to so withhold, or taking any other action
reasonably required to satisfy the withholding obligation of the Company or the applicable
Subsidiary. 9. Continued Employment Not Presumed.Nothing in this Agreement, the Plan or any document
describing it nor the grant of an option shall give the Optionee the right to continue in
employment with the Company or any of its Subsidiaries or affect the right of the Company or a
Subsidiary to terminate the employment of the Optionee with or without cause. 10. Non-Competition Covenants. a. The provisions of this subparagraph a. shall apply both during normal working hours and at
all other times including, but not limited to, nights, weekends and vacation time, while Optionee
is employed by the Company or any Subsidiary. Optionee shall not directly or indirectly (i) engage
in any employment, business, or activity that is competitive with the business of the Company or
any Subsidiary, (ii) assist any other person or organization in competing with, or in preparing to
engage in competition with, the business of the Company or any Subsidiary. Direct competition shall
include, but not be limited to, the design, development, production, promotion or sale of products,
software, or services competitive with those of the Company or any Subsidiary. In addition,
Optionee shall not directly or indirectly (i) engage in any employment, business, or activity that
is competitive with either (A) the proposed business of the Subsidiary that employs
Optionee (Employing Subsidiary) or (B) any proposed business of any of the Companys other
Subsidiaries (the Non-Employing Subsidiaries) of which Optionee has actual knowledge, or (ii)
assist any other person or organization in competing with, or in preparing to engage in competition
with, either (A) the proposed business of the
Employing Subsidiary or (B) any proposed business of any Non-Employing Subsidiary of which Optionee
has actual knowledge.




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b. The provisions of this subparagraph b. shall apply during Optionees employment with the
Company or any Subsidiary and for a period of six months after Optionee ceases to be employed by
the Company or any Subsidiary. Optionee shall not directly or indirectly solicit to conduct any
Competitive Business with, or conduct any Competitive Business with, any (i) then-current customer
of the Employing Subsidiary or (ii) any person that has been a customer of the Employing Subsidiary
within the six months prior to the time of Optionees separation from employment. The phrase
Competitive Business means the line(s) of business(es) conducted by the Employing Subsidiary. c. The provisions of this subparagraph c. shall apply during Optionees employment with the
Company or any Subsidiary and for a period of 12 months after Optionees separation from
employment. Optionee shall not directly or indirectly solicit to hire, or cause to be hired, any
employee of the Company or any Subsidiary as an employee or agent of, or consultant to, any
business enterprise that Optionee is associated with. d. Each non-competition covenant of Optionee contained in the preceding provisions of this
Paragraph 10 (the non-competition covenant) shall be construed as an agreement independent of any
other provision of this Agreement and the existence of any claim or cause of action of Optionee
against the Company or any Subsidiary, whether predicated on this Agreement or otherwise, shall not
constitute a defense to the enforcement by the Company or any Subsidiary of such non-competition
covenant. e. The Company and Optionee have in good faith used their best efforts to make each
non-competition covenant contained in the preceding provisions of this Paragraph 10 reasonable in
both scope and in duration. It is not anticipated, nor is it intended, by either party to this
Agreement that any court or other tribunal having jurisdiction over the matter will find it
necessary to reform any non-competition covenant to make it reasonable in both scope and in
duration, or otherwise. If any non-competition covenant is deemed by a tribunal having
jurisdiction over the matter to be unlawful or unenforceable, such provision will be deemed
severable from this Agreement and such provision will be limited or eliminated to the minimum
extent necessary so that the remaining provisions of this Agreement shall otherwise remain in full
force and effect and be enforceable. Furthermore, in lieu of such unlawful or unenforceable
provision, there shall be added automatically as part of this Agreement a provision as similar in
terms as may be possible and be enforceable. f. Optionee is agreeing to the provisions of this Paragraph 10 in consideration of the grant
of this Option. The provisions of this Paragraph 10 shall be valid and enforceable by the Company
and its Subsidiaries, regardless of whether or not any of this Option granted hereunder actually
becomes exercisable, or whether or not




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Optionee actually exercises any rights under this Option. In the event of any conflict or
inconsistency between any provision of this Paragraph 10 and any similar or analogous provision of
any other agreement (either currently in effect or that may be entered into in the future) between
Optionee, on the one hand, and the Company or any Subsidiary, on the other hand, whichever
provision is most favorable to the Company or such Subsidiary shall govern. 11. Option Issued Pursuant to Plan. This Option is issued pursuant to and subject to the
terms and conditions and the restrictions as set forth in the Plan, and in the event of any
inconsistency, the provisions of the Plan shall govern, provided that no amendment shall be made to
the Plan subsequent to the date hereof that impairs the Optionees rights under this Option without
the Optionees written consent. 12. No Liability of Option.This Option is not liable for or subject to, in whole or in
part, the debts, contracts, liabilities or torts of the Optionee nor shall it be subject to
garnishment, attachment, execution, levy or other legal or equitable process. 13. No Assignment.This Option is not transferable otherwise than by will or the laws of
descent and distribution, and is exercisable during the Optionees lifetime only by Optionee.
Without limiting the generality of the foregoing, this Option may not be assigned, transferred
(except as aforesaid), pledged or hypothecated in any way (whether by operation of law or
otherwise), and shall not be subject to execution, attachment, or similar process, without the
prior written consent of the Company. Any attempted assignment, transfer, pledge, or hypothecation
contrary to the provisions hereof shall be void and ineffective for all purposes. 14.Governing Law.This Agreement has been executed in, and shall be deemed to be
performable in, Dallas, Dallas County, Texas. The parties agree that this Agreement shall be
governed by and construed in accordance with the laws of the State of Texas (excluding its conflict
of laws rules). The parties further agree that the courts of the State of Texas, and any courts
whose jurisdiction is derivative on the jurisdiction of the courts of the State of Texas, shall
have personal jurisdiction over all parties to this Agreement. 15.Entire Agreement.By signing the Signature Page, the Optionee agrees to the terms of
this Option. Except for the Plan, this Agreement constitutes the entire agreement between the
parties pertaining to the subject matter hereof and supersedes all prior and contemporaneous
agreements, representations and understandings of the parties. No supplement, modification or
amendment of this Agreement shall be binding unless executed in writing by the party to be charged
therewith. No waiver of any of the provisions of this Agreement shall be deemed, or shall
constitute a waiver of any other provision, whether or not similar, nor shall any waiver constitute
a continuing waiver. 16.Notice.Other than any Exercise Notice, any notice required or permitted to be given
under the Plan or this Agreement shall be in writing and delivered in person or sent by registered
or certified mail, return receipt requested, first-class postage prepaid, (i) if to




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the Optionee, at the address shown on the books and records of the Company or at the Optionees
place of employment, or (ii) if to the Company, at 2711 N. Haskell Avenue, Suite 2300, LB 36,
Dallas, Texas 75204-2960: Attention: Treasurer, or any other address that may be given by either
party to the other party by notice pursuant to this Paragraph. Any notice other than any Exercise
Notice, if sent by registered or certified mail, shall be deemed to have been given when received. ZIX CORPORATIONBy:John A. RyanChairman & Chief Executive Officer