AMENDED AND RESTATED SEVERANCE AGREEMENT

Exhibit 10.27

Execution Version

AMENDED AND RESTATED SEVERANCE AGREEMENT

     THIS AMENDED AND RESTATED SEVERANCE AGREEMENT (this “Agreement”), entered into as of December 18, 2008, is made and entered into between Zix Corporation, a Texas corporation (the “Company”), and Richard D. Spurr (“Employee”) and hereby amends and restates that certain severance agreement, dated December 10, 2007 between the parties.

     WHEREAS, Employee is currently employed by the Company;

     WHEREAS, Employee is willing to continue working for the Company on an “at-will” basis;

     NOW, THEREFORE, in consideration of the foregoing and of the respective covenants and agreements of the parties herein contained, the parties agree as follows:

1. Definitions .

     A.  Acquiring Person . An “Acquiring Person” shall mean any person (including any “person” as such term is used in Sections 13(d)(3) or 14(d)(2) of the Exchange Act that, together with all Affiliates and Associates of such person, is the beneficial owner (as the term “beneficial owner” is defined under Rule 13d-3 or any successor rule or regulation promulgated under the Exchange Act)) of 10% or more of the outstanding Common Stock. The term “Acquiring Person” shall not include the Company, any majority-owned subsidiary of the Company, any employee benefit plan of the Company or a majority—owned subsidiary of the Company, or any person to the extent such person is holding Common Stock for or pursuant to the terms of any such plan. For the purposes of this Agreement, a person who becomes an Acquiring Person by acquiring beneficial ownership of 10% or more of the Common Stock at any time after the date of this Agreement shall continue to be an Acquiring Person whether or not such person continues to be the beneficial owner of 10% or more of the outstanding Common Stock.

     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.  Cause . “Cause” shall mean any of the following shall have occurred: (1) the intentional and continued failure by Employee to substantially perform Employee’s employment duties, such intentional action involving willful and deliberate malfeasance or gross negligence in the performance of Employee’s duties (other than any such failure resulting from Employee’s incapacity due to physical or mental illness), after written demand for substantial performance is delivered by the Company’s Board of Directors (hereinafter, referred to as the “Board”) that specifically identifies the manner in which the Board of Directors believes Employee has not substantially performed Employee’s duties and that is not cured within five business days after notice thereof by the Company to Employee; (2) the intentional engaging by Employee in misconduct that is materially injurious to the Company; (3) the conviction of Employee or a plea of nolo contendere, or the substantial equivalent to either of the foregoing, of or with respect to, any felony; (4) the commission of acts by Employee of moral turpitude that are injurious to the

Company; (5) a breach by Employee of the “confidentiality and invention” agreement between the Company and Employee; (6) a breach by Employee of Section 8 of this Agreement; or (7) a breach by Employee of the Company’s “Code of Ethics for Senior Officers,” as currently in effect or amended from time-to-time. For purposes of this definition, no act, or failure to act, on Employee’s part shall be considered “intentional” unless done, or omitted to be done, by him not in good faith and without reasonable belief that his action or omission was in, or not opposed to, the best interest of the Company.

     Notwithstanding the foregoing, Employee shall not be deemed to have been terminated for Cause without (1) reasonable written notice to Employee, setting forth the reasons for the Company’s intention to terminate for Cause; (2) an opportunity for Employee, together with his counsel, to be heard before the Board (or an authorized representative thereof; and (3) delivery to Employee of a written notice of termination from the Board (or its authorized representative) finding that, in the good faith opinion of the Board (or its authorized representative), Employee engaged in the conduct set forth above in clause (1) or (2) of the preceding paragraph or an event specified in clause (3), (4), (5), (6) or (7) of the preceding paragraph has occurred.

     D.  Change in Control . A “Change in Control” of the Company shall have occurred if any of the following events shall occur during the term of Employee’s employment;

     (1) The Company is merged, consolidated or reorganized into or with another corporation or other legal person, other than an Affiliate, and as a result of such merger, consolidation or reorganization, 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;

     (2) The Company sells all or substantially all of its assets to any other corporation or other legal person, other than an Affiliate, and as a result of such sale, 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 this provision shall not apply to a registered public offering of securities of a subsidiary of the Company, which offering is not part of a transaction otherwise a part of or related to a Change in Control);

     (3) Any Acquiring Person has become the beneficial owner (as the term “beneficial owner” is defined under Rule 13d-3 or any successor rule or regulation promulgated under the Exchange Act) 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 which are entitled to vote to elect any class of directors;

     (4) If, at any time, the Continuing Directors then serving on the Board cease for any reason to constitute at least a majority thereof;

     (5) 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; or

     (6) Such other events that cause a Change in Control of the Company, as determined by the Board in its sole discretion.

     E.  Continuing Director . A “Continuing Director” shall mean a director of the Company who (1) 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 (2) was either (a) a member of the Board on the date of this Agreement or (b) 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.

     F.  Company . The “Company” shall mean Zix Corporation, a Texas corporation, or its successors in interest, as the context requires.

     G.  Disability . “Disability” shall mean that Employee is unable to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment that can be expected to result in death or can be expected to last for a continuous period of not less than 12 months.

     H.  Exchange Act . “Exchange Act” shall mean the Securities Exchange Act of 1934, as amended.

     I.  Good Reason . “Good Reason” shall mean (1) any material diminution in Employee’s duties, it being understood and agreed that if all or substantially all of the assets of the Company’s e-Prescribing line of business, the Company’s Email Encryption line of business, or any other material line of business is sold, leased, licensed or otherwise transferred for value to a non-Affiliate, Employee’s duties will be materially reduced and Employee shall have “Good Reason” to resign employment pursuant to this clause (1); (2) the assignment of duties or positions that would necessitate a material change in the location of Employee’s home (presently in North Dallas, Texas); or (3) the Company’s failure to maintain directors and officers liability coverage for Employee in an amount equal to at least $10,000,000.

          Notwithstanding the preceding provisions, Employee shall not be permitted to resign employment for “Good Reason” until (a) Employee has provided to the Company notice of the existence of the good reason condition within 90 days of its initial existence and (b) the Company has not remedied the good reason condition within a period of 30 days from the Company’s receipt of such notice. Following the satisfaction of (a) and (b), Employee must exercise his right to resign for Good Reason within 30 days (i.e., such Good Reason resignation must occur within 150 days of the occurrence of the good reason event), with the day immediately following the existence of the good reason condition being day “1.”

2. Termination Without Cause Payment . If the Company terminates Employee’s employment other than for Cause, the Company shall pay to Employee an amount equal to 12 months of Employee’s base salary, using Employee’s highest monthly base salary during the

term of Employee’s employment (the “Termination Without Cause Payment”) pursuant to Section 6. The Company specifically acknowledges that Employee will incur a termination of employment for a reason other than Cause if (i) a material portion of the Company’s e-Prescribing line of business, the Company’s Email Encryption line of business, or any other material line of business is sold, leased, licensed or otherwise transferred for value (the “Transfer”) to a non-Affiliate (“Non-Affiliate Transferee”) and (ii) in connection with such Transfer the Company involuntarily terminates Employee’s employment with the Company and its Affiliates (regardless of whether Employee accepts employment with the Non-Affiliate Transferee or one of its Affiliates).

          As an additional component of the Termination Without Cause Payment, the Company shall pay the applicable premiums for COBRA continuation benefits under the applicable Company benefit plans, on a monthly basis beginning with the effective date of Employee’s loss of coverage by reason of Employee’s separation from employment and continuing until the earlier of (a) 12 months following the loss of coverage by reason of Employee’s separation from employment or (b) the date Employee obtains medical coverage under a new employer’s group health plan.

          Employee shall not be entitled to more than one Termination Without Cause Payment pursuant to this Agreement.

3. Change In Control Payment . If Employee resigns from employment (subject to the notice and cure provisions noted below) with the Company and its Affiliates following a Change in Control for a “Change in Control Good Reason,” as such term is defined below, the Company shall pay to Employee an amount equal to 12 months of Employee’s base salary, using Employee’s highest monthly base salary during the term of Employee’s employment (the “Change In Control Payment”) pursuant to Section 6.

     A “Change in Control Good Reason” shall mean (i) a material diminution in the Employee’s authority, duties or responsibilities, (ii) a material diminution in the Employee’s base salary, (iii) a material change in the geographic location at which the Employee must perform services, (iv) a material diminution in the authority, duties, or responsibilities of the supervisor to whom the Employee is required to report, including a requirement that the Employee report to a corporate officer or employee instead of the board of directors (or similar governing body), (v) a material diminution in the budget over which the Employee retains authority, or (vi) any other event that constitutes a material breach by the Company of the agreement under which the Employee provides services.

     Notwithstanding the preceding provisions, Employee shall not be permitted to resign employment for a “Change in Control Good Reason” until (a) Employee has provided to the Company notice of the existence of the good reason condition within 90 days of its initial existence and (b) the Company has not remedied the good reason condition within a period of 30 days from the Company’s receipt of such notice. Following the satisfaction of (a) and (b), Employee must exercise his right to resign for a Change in Control Good Reason within 60 days (i.e., such Change in Control Good Reason resignation must occur within 180 days of the

occurrence of the good reason event), with the day immediately following the existence of the good reason condition being day “1.”

     As an additional component of the Change In Control Payment, the Company shall pay the applicable premiums for COBRA continuation benefits under the applicable Company benefit plans, on a monthly basis beginning with the effective date of Employee’s loss of coverage by reason of Employee’s separation from employment and continuing until the earlier of (a) 12 months following the loss of coverage by reason of Employee’s separation from employment or (b) th