UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities

Exchange Act of 1934 (Amendment No.                )

Filed by the Registrant   ☒                            Filed by a Party other than the Registrant  ☐

Check the appropriate box:

ZIX CORPORATION

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check the appropriate box):

ZIX CORPORATION

2711 North Haskell Avenue

Suite 2300, LB 36, Dallas, Texas 75204-2960

To our Shareholders,

You are cordially invited to attend the Annual Meeting of Shareholders of Zix Corporation, which will take place Wednesday, June 9, 2021, at 10:00 a.m. Central Time. The Annual Meeting will be a virtual meeting held over the Internet. You will be able to attend the virtual Annual Meeting, vote your shares electronically, and submit your questions during the live audio-only webcast of the virtual Annual Meeting by visiting www.virtualshareholdermeeting.com/ZIXI2021 and entering your control number contained on your proxy card. Details of the business to be conducted at the Annual Meeting are given in the Official Notice of the Meeting, Proxy Statement and form of proxy that accompany this letter.

Regardless of whether you plan to attend the virtual Annual Meeting, we encourage you to vote in advance so that we will know that we have a quorum of shareholders entitled to vote at the meeting. When you vote in advance, please indicate your intention to attend the virtual Annual Meeting. Please see the Question and Answer section of the enclosed Proxy Statement for instructions if you plan to attend the virtual Annual Meeting.

Whether or not you are able to attend the virtual Annual Meeting, it is important that your shares be represented and voted. Your prompt vote over the Internet, by telephone via toll-free number, or by written proxy will save us the expense and extra work of additional proxy solicitation. Voting by any of these methods at your earliest convenience will ensure your representation at the Annual Meeting if you choose not to attend the virtual Annual Meeting. If you decide to attend the virtual Annual Meeting, you will be able to vote electronically, even if you have personally submitted your proxy. Please review the instructions on the proxy card or the information forwarded by your bank, broker, or other holder of record concerning each of these voting options.

We appreciate your continued interest in Zix Corporation.

ZIX CORPORATION

2711 North Haskell Avenue

Suite 2300, LB 36

Dallas, Texas 75204-2960

Whether or not you expect to attend the virtual meeting, we urge you to vote your shares at your earliest convenience to ensure the presence of a quorum at the meeting. Promptly voting your shares via the Internet, by telephone via toll-free number, or if you received a paper copy of the proxy card, by signing, dating, and returning the proxy card in the enclosed postage-paid envelope will save us the expense and extra work of additional solicitation. Because your proxy is revocable at your option, submitting your proxy now will not prevent you from voting your shares at the virtual meeting if you desire to do so. Please refer to the voting instructions included on your proxy card or the voting instructions forwarded by your bank, broker, or other holder of record.

Questions and Answers About the Annual Meeting and Voting

This Question and Answer section provides some background information and brief answers to several questions you might have about the enclosed proposals. We encourage you to read this Proxy Statement in its entirety.

What is a proxy?

A proxy is your legal designation of another person, called a proxy holder, to vote the shares that you own. If you designate someone as your proxy holder in a written document, that document is called a proxy.

When I vote my shares, whom am I designating as my proxy?

We have designated Noah F. Webster, our Chief Legal & Compliance Officer and Corporate Secretary, and David E. Rockvam, our Chief Financial Officer, to act as proxy holders at the Annual Meeting as to all shares for which proxy cards are returned or voting instructions are provided by Internet or telephonic voting.

What is a proxy statement?

A proxy statement is a document that the Securities and Exchange Commission (the “SEC”) regulations require us to give you when we ask you to sign a proxy card designating the proxy holders described above to vote on your behalf.

What is the record date?

The record date for the Annual Meeting is April 12, 2021. The record date is established by our Board of Directors as required by Texas law. Only shareholders of record of our common stock and our Series A Preferred Stock (collectively, our “Voting Shareholders”) at the close of business on the record date are entitled to receive notice of the Annual Meeting and to vote their shares electronically during the live audio-only webcast of the Annual Meeting, or by telephone from the U.S. using the toll-free telephone number on the proxy card, or by the Internet, using the procedures and instructions described on the proxy card and other enclosures.

What is the difference between a shareholder of record and a shareholder who holds stock in street name, also called a “beneficial owner”?

If your shares are registered in your name at our stock registrar and transfer agent, Computershare Trust Company, N.A., you are a shareholder of record.

If your shares are registered at our stock registrar and transfer agent, Computershare Trust Company, N.A., in the name of a broker, bank, trustee, nominee, or other similar shareholder of record, your shares are held in street name and you are the beneficial owner of the shares.

What methods can I use to vote?

By Written Proxy. All Voting Shareholders may vote by mailing the written proxy card.

By Telephone and Internet Proxy. All Voting Shareholders of record may vote by telephone from the U.S. using the toll-free telephone number on the proxy card, or by the Internet, using the procedures and instructions described on the proxy card and other enclosures. Street name holders may vote by telephone or the Internet if their bank, broker, or other Voting Shareholder of record makes those methods available, in which case the bank, broker, or other Voting Shareholder of record will enclose the instructions with the Proxy Statement. The telephone and Internet voting procedures, including the use of control numbers, are designed to authenticate Voting Shareholders’ identities, to allow Voting Shareholders to vote their shares, and to confirm that their instructions have been properly recorded.

By Electronic Submission during the Virtual Annual Meeting. Voting Shareholders of record and street name holders may vote electronically during the live audio-only webcast of the Annual Meeting as described in the following question and answer.

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How do I cast an electronic ballot during the live audio-only webcast of the Annual Meeting?

Voting Shareholders of Record. To log in to the Annual Meeting and to cast your vote electronically during the virtual meeting, you will need the unique control number which appears on the notice regarding the availability of proxy materials, the proxy card (printed in the box and marked by the arrow) and the instructions that accompanied the proxy materials.

Street Name Holders. To log in to the Annual Meeting and to cast your vote electronically during the virtual meeting, you will need to ask your broker or bank for a control number and your broker or bank will provide you with instructions that you must follow to have your shares voted. Please note that if you own shares in street name and you are issued a legal proxy, any previously executed proxy will be revoked and your vote will not be counted unless you attend the virtual meeting and vote your shares electronically.

What will occur at the Annual Meeting?

First, we will determine whether we have a quorum of shares represented at the Annual Meeting to conduct business. If a quorum is not present at the Annual Meeting, we will adjourn or reschedule the meeting. If enough shares are represented at the Annual Meeting to conduct business, then we will vote on the proposals described in this Proxy Statement and any other business properly brought before the meeting or any adjournment or postponement thereof. We know of no other matters that will be presented for consideration at the Annual Meeting. If, however, other matters or proposals are presented and properly come before the meeting, the proxy holders intend to vote all proxies in accordance with their best judgment in the interest of Zix Corporation and our shareholders.

A representative of Whitley Penn LLP, our independent registered public accounting firm, is expected to be virtually present at the Annual Meeting and will be afforded the opportunity to make a statement, if that representative so desires, and to respond to appropriate questions. A representative of Broadridge Financial Solutions, Inc. will count the votes and act as the independent inspector of election.

What is a quorum?

The holders of a majority of the shares entitled to vote at the Annual Meeting must be represented at the virtual meeting in person or by proxy to have a quorum for the transaction of business at the meeting and to act on the matters specified in the notice. A Voting Shareholder will be deemed to be represented at the virtual Annual Meeting if such shareholder:

As of the record date, there were 57,058,008 shares of common stock outstanding and entitled to vote at the Annual Meeting, held by or through385 holders of record. Each share of our common stock is entitled to one vote.

As of the record date, 100,206 shares of our Series A Preferred Stock were outstanding and entitled to vote on an as-converted basis at the Annual Meeting, held by or through one holder of record. As of the record date, the 100,206 shares of Series A Preferred Stock were convertible into 19,733,971 shares of our common stock.

Our Voting Shareholders are entitled to cast an aggregate of 76,791,979 votes at the Annual Meeting, so a quorum equals 38,395,991 shares of our common stock (in each case, including the Series A Preferred Stock on an as-converted basis).

As of the record date, there were no shares of our Series B Preferred Stock outstanding.

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What proposals are Voting Shareholders being asked to consider at the Annual Meeting?

At the Annual Meeting, we will ask our Voting Shareholders to consider and vote on the following:

What are my voting choices on Proposal 1 for director nominees?

For the vote on the election of the director nominees, Voting Shareholders may:

The Board recommends that you vote “FOR” Proposal 1 and “FOR” each of the director nominees.

What vote is needed to elect directors?

The eight nominees will be elected who receive a plurality of the FOR votes out of all votes cast (either FOR or WITHHELD) electronically during the live audio-only webcast or by proxy at the Annual Meeting.

What is a plurality of the votes?

In order to be elected, a director nominee does not have to receive a majority of FOR votes cast out of all votes cast either affirmatively or withheld electronically during the live audio-only webcast or by proxy at the Annual Meeting. Instead, the eight nominees who will be elected are those who receive the most FOR votes of all the votes cast on Proposal 1 electronically during the live audio-only webcast or by proxy at the meeting.

What happens if a director nominee does not receive a majority of FOR votes?

Under our Director Nomination and Election Policies, each director nominee in an uncontested election tenders his or her conditional resignation to the Corporate Secretary before the Annual Meeting. That resignation offer becomes effective automatically if the tendering director nominee fails to receive a majority of FOR votes cast out of all votes cast either affirmatively or withheld electronically during the live audio-only webcast or by proxy at the Annual Meeting (“Majority WITHHELD Vote”). The Nominating and Corporate Governance Committee of the Board (the “Nominating and Corporate Governance Committee”) then recommends to the Board whether to accept the offered resignation. The Board will, within 90 days after the certification of voting results, decide whether or not to accept the offered resignation. In general, any director nominee who receives a Majority WITHHELD Vote will not participate in the Nominating and Corporate Governance Committee recommendation or the Board decision regarding an offered resignation. If all members of the Nominating and Corporate Governance Committee received a Majority WITHHELD Vote, then the independent directors who did not receive a Majority WITHHELD Vote will appoint a committee among themselves to consider and make a recommendation to the Board with respect to the offered resignations. If three or fewer directors receive a majority of FOR votes cast out of all votes cast either affirmatively or withheld electronically during the live audio-only webcast or by proxy at the Annual Meeting, then all directors (including those who received a Majority WITHHELD Vote) may participate in the Board’s decision whether to accept or not to accept the

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offered resignations. The Company will promptly disclose the Board’s decision in a Current Report on Form 8-K, including the reasons a resignation is not accepted.

What are my voting choices on Proposal 2, the ratification of the appointment of Whitley Penn LLP as the Company’s independent registered public accounting firm?

For the vote on the ratification of the appointment of our independent registered public accounting firm, Voting Shareholders may:

Our Board recommends that you vote “FOR” Proposal 2.

What vote is required to ratify the appointment of the Company’s independent registered public accounting firm?

The proposal to ratify the appointment of our independent registered public accounting firm requires the FOR vote of the holders of a majority of the shares entitled to vote on the proposal and represented electronically during the live audio-only webcast or by proxy at the Annual Meeting.

What are my voting choices on Proposal 3, the advisory vote to approve our executive compensation?

For the advisory vote on executive compensation, Voting Shareholders may:

Our Board recommends that you vote “FOR” Proposal 3.

What vote is required for the advisory approval of the Company’s executive compensation?

The Company’s executive compensation will be approved by the Voting Shareholders, on an advisory basis, if the votes cast FOR the proposal are a majority of the shares entitled to vote on the proposal and represented electronically during the live audio-only webcast or by proxy at the Annual Meeting.

How often will the Company hold an advisory vote to approve executive compensation?

At our 2017 Annual Meeting of Shareholders, our shareholders voted, in an advisory vote, on various frequencies for conducting future advisory votes with respect to compensation of our named executive officers, with an annual frequency receiving the most advisory votes that were cast. After considering those voting results and other factors, our Board determined that the Company would hold an annual advisory vote on the compensation of our named executive officers until (a) the next required vote on the frequency of shareholder votes on the compensation of our named executive officers or (b) the Board otherwise determines that a different frequency for such advisory votes is in the best interests of our shareholders.

What are my voting choices on Proposal 4, the approval of the 2021 Plan?

For the vote on the approval of the 2021 Plan, shareholders may:

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Our Board recommends that you vote “FOR” Proposal 4.

What vote is required for the approval of the 2021 Plan?

The proposal to approve the 2021 Plan requires the FOR vote of the holders of a majority of the shares entitled to vote on the proposal and represented in person or by proxy at the Annual Meeting and entitled to vote thereon.

What if a Voting Shareholder does not specify a choice for a matter when returning a proxy?

Voting Shareholders should specify their choice for each proposal described on the enclosed proxy card. Proxy cards that are signed and returned will be voted FOR proposals described in this proxy statement for which no specific instructions are given.

How are withheld votes, abstentions and broker non-votes counted?

Both abstentions and broker non-votes are counted as “present” for purposes of determining the existence of a quorum at the Annual Meeting. Shares voted WITHHELD as to a director nominee on Proposal 1 will have no effect on the election of the nominees, but, for purposes of the Majority WITHHELD Vote and the effectiveness of a nominee’s conditional resignation, will count as votes against the indicated nominee. Shares voted ABSTAIN on Proposals 2, 3 and 4 will have the same effect as votes cast AGAINST that proposal. Broker non-votes will not be included in vote totals and will not affect the outcome of the vote on the proposals.

Why did I receive more than one Proxy Statement?

If you received more than one Proxy Statement, your shares are probably registered in different names or are in more than one account. Please vote each proxy card that you receive.

What if I want to change my vote?

You may revoke your vote on any proposal at any time before the Annual Meeting for any reason. To revoke your proxy before the meeting, write to Zix Corporation, Attention: Corporate Secretary, 2711 North Haskell Avenue, Suite 2300, LB 36, Dallas, Texas 75204-2960. You will need to include a copy of your earlier voted proxy and may be required to provide other information to facilitate the administrative steps actually required to properly revoke your prior proxy and properly record the revocation. You may also attend the virtual Annual Meeting and change your vote by electronically voting your shares. Attendance at the virtual Annual Meeting will not cause your previously granted proxy to be revoked unless you specifically so request or cast your vote electronically at the virtual meeting.

Where will I find the voting results of the Annual Meeting?

We will announce the preliminary voting results at the Annual Meeting and will publish the preliminary or final voting results in a Current Report on Form 8-K that we will file with the SEC within four business days after the Annual Meeting. If the voting results are not final when that Current Report is filed, we will publish the final voting results in a Current Report on Form 8-K that we will file with the SEC within four business days after the final voting results are determined. You may request a copy of either Current Report at investor.zixcorp.com or by contacting Investor Relations at (949)-574-3860.

How can I submit a question for the Annual Meeting?

By accessing www.proxyvote.com, our shareholders will be able to submit questions in writing in advance of our Annual Meeting, vote, view the annual meeting procedures, and obtain copies of proxy materials and our 2020 Annual Report on Form 10-K. Shareholders may also submit questions in writing on the day of or during the Annual Meeting at www.virtualshareholdermeeting.com/ZIXI2021. Shareholders will need their unique control number which appears on the notice regarding the availability of proxy materials, the proxy card (printed in the box and marked by the arrow) and the instructions that accompanied the proxy materials.

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As part of the Annual Meeting, we will hold a live question and answer session, during which we intend to answer all questions submitted in writing before or during the virtual meeting in accordance with the annual meeting procedures, as time permits. Questions and answers will be grouped by topic and substantially similar questions will be grouped and answered once.

What if I need Technical Assistance?

Beginning 20 minutes prior to the start of and during the virtual Annual Meeting, we will have a support team ready to assist shareholders with any technical difficulties they may have accessing or hearing the virtual meeting. If you encounter any difficulties accessing the virtual meeting during the check-in or meeting time, please call the technical support number that will be posted on the Virtual Shareholder Meeting log-in page.

Where can I find additional information? Who can help answer my questions?

You should carefully review the entire Proxy Statement, which contains important information regarding the proposals, before voting. The section titled “WHERE YOU CAN FIND MORE INFORMATION” describes additional sources from which to obtain this Proxy Statement, our public filings under the Securities Exchange Act of 1934 and other information about our Company. Additionally, a copy of this Proxy Statement is available on our Company’s website at investor.zixcorp.com.

If you would like additional copies of this Proxy Statement or other documents that we have filed with the SEC that are incorporated by reference into this Proxy Statement, free of charge, or if you have questions about the proposals or the procedures for voting your shares, please contact: Zix Corporation, Attention: Corporate Secretary, 2711 North Haskell Avenue, Suite 2300, LB 36, Dallas, Texas 75204-2960 or (214) 370-2000.

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ZIX CORPORATION

2711 North Haskell Avenue

Suite 2300, LB 36

Dallas, Texas 75204-2960

Purpose of Annual Meeting

The purpose of the Annual Meeting is to obtain approval for the proposals described in this Proxy Statement and to consider any other business properly brought before the Annual Meeting or any adjournment or postponement thereof. At the Annual Meeting, we will ask Voting Shareholders to consider and vote on the following proposals:

Record Date and Shares Outstanding

Only shareholders who owned shares of our common stock and our Series A Preferred Stock at the close of business on April 12, 2021, referred to in this Proxy Statement as the “Record Date,” are entitled to notice of, and to vote at, the Annual Meeting. As of the Record Date, 57,058,008 shares of our common stock were outstanding and entitled to vote at the Annual Meeting. Holders of our common stock are entitled to one vote, in person or by proxy, for each share of common stock held in their name on the Record Date.

As of the Record Date, 100,206 shares of our Series A Preferred Stock were outstanding and entitled to vote on an as-converted basis at the Annual Meeting. As of the Record Date, the 100,206 shares of Series A Preferred Stock were convertible into 19,733,971 shares of common stock.

As of the record date, there were no shares of our Series B Preferred Stock outstanding.

Quorum

A majority of the outstanding shares of our common stock entitled to vote at the Annual Meeting (including the Series A Preferred Stock on an as-converted basis) must be represented, electronically during the live audio-only webcast or by proxy, at the Annual Meeting to constitute a quorum to conduct business at the meeting. As of the Record Date, 76,791,979 shares of our common stock (including the Series A Preferred Stock on an as-converted basis) were outstanding and entitled to vote at the Annual Meeting, so we will require a quorum of at least 38,395,991 shares of our common stock (including the Series A Preferred Stock on an as-converted basis) represented at the Annual Meeting in order to conduct business at the meeting.

Revocability of Proxies

You may revoke your proxy at any time before it is exercised. Execution of the proxy will not affect your right to virtually attend the Annual Meeting. Revocation may be made before the Annual Meeting by written revocation or through a duly executed proxy bearing a later date sent to Zix Corporation, Attention: Corporate Secretary, 2711 North Haskell Avenue, Suite 2300, LB 36, Dallas, Texas 75204-2960; or your proxy may be revoked electronically during the live audio-only webcast of the Annual Meeting by specific written notice to the Secretary during the live audio-only webcast of the Annual Meeting before the voting of the proxy or by the electronic vote of your shares at the virtual meeting. Any revocation sent to the Company must include the shareholder’s name and must be received before the Annual Meeting to be effective.

How Your Proxy Will Be Voted

In the absence of specific instructions to the contrary, shares represented by properly executed proxies received by the Company, including unmarked signed proxies, will be voted FOR each of the proposals that will be considered at the Annual Meeting. In addition, if any other matters properly come before the Annual Meeting the persons named as proxy holders in the enclosed proxy card will have discretion as to how they will vote the shares they represent. Other than the proposals described in this Proxy Statement, we have not received notice of any matters that may properly be presented at the Annual Meeting.

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Dissenters’ Rights

Under Texas law, shareholders are not entitled to dissenters’ rights with respect to any of the proposals that will be considered at the Annual Meeting.

Tabulation of Votes

Votes cast at the Annual Meeting will be tabulated by a representative of Broadridge Financial Solutions, Inc. as the independent inspector of election.

Vote Required to Approve Proposals

Proposals

PROPOSAL 1 — ELECTION OF DIRECTORS

Our Voting Shareholders will vote on the election of eight members of our Board at the Annual Meeting. Each director will serve until the next Annual Meeting of Shareholders and until the director’s successor is duly elected and qualified, unless earlier removed in accordance with our bylaws.

The nominees for election to our Board are:

For biographical and other information regarding the nominees for director, please see “OTHER INFORMATION YOU NEED TO MAKE AN INFORMED DECISION — Directors.” For information on our directors’ compensation, please see “INFORMATION ON THE COMPENSATION OF DIRECTORS.”

Each of the persons nominated for election to our Board has agreed to stand for election. Our Board has no reason to believe that any of the nominees will be unable or unwilling to serve if elected, and to the knowledge of the Board, each of the nominees intends to serve the entire term for which election is sought. Our bylaws provide that the Board may reduce the number of positions on our Board. In addition, our bylaws provide that the Board may fill any vacancy in the Board by the affirmative vote of a majority of the remaining directors.

The eight nominees who receive the greatest number of FOR votes (also called a “plurality” of FOR votes) will be elected as directors. Broker non-votes will not be included in vote totals and will not affect the outcome of the vote on this proposal. A vote WITHHELD as to any director will have no effect on the election of the nominees, but, for purposes of the Majority WITHHELD Vote (as described in the Question and Answer section of this Proxy Statement) and the effectiveness of a nominee’s conditional resignation, will be counted as a vote against the election of that director.

OUR BOARD RECOMMENDS THAT YOU VOTE

FOR PROPOSAL 1 AND FOR EACH DIRECTOR NOMINEE NAMED ABOVE.

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PROPOSAL 2 — RATIFICATION OF APPOINTMENT OF ACCOUNTANTS

The Audit Committee of the Board (the “Audit Committee”) has recommended, and the Board has appointed, Whitley Penn LLP as our independent registered public accounting firm for the fiscal year ending December 31, 2021. Services provided to the Company and its subsidiaries by Whitley Penn LLP in fiscal 2020 are described under “Independent Registered Public Accountants.”

We are asking our Voting Shareholders to ratify the appointment of Whitley Penn LLP as our independent registered public accounting firm for the 2021 fiscal year. Although ratification is not required by our bylaws or otherwise, the Board is submitting the appointment of Whitley Penn LLP to our Voting Shareholders for ratification as a matter of good corporate practice.

A representative of Whitley Penn LLP will be present at the Annual Meeting to respond to appropriate questions and to make any statements that the firm may desire.

Votes cast FOR Proposal 2 by a majority of the shares of our common stock (including the Series A Preferred Stock on an as-converted basis) represented at the Annual Meeting is required to approve Proposal 2. Shares voted to ABSTAIN as to Proposal 2 will be counted as represented at the meeting and will have the same effect as a vote against Proposal 2.

If our Voting Shareholders do not approve Proposal 2, the appointment of Whitley Penn LLP will be reconsidered by our Audit Committee and our Board. Even if Proposal 2 is approved, the Audit Committee in its discretion may select a different independent registered public accounting firm if it determines that a change would be in the best interests of the Company and our shareholders and otherwise complies with all regulations of the SEC regarding a change in public accounting firms.

OUR BOARD RECOMMENDS

THAT YOU VOTE FOR PROPOSAL 2.

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PROPOSAL 3 — APPROVE, ON AN ADVISORY BASIS, THE COMPENSATION OF OUR NAMED EXECUTIVE OFFICERS

The Dodd-Frank Wall Street Reform and Consumer Protection Act enables the Company’s Voting Shareholders to vote to approve, on an advisory (nonbinding) basis, the compensation of the Company’s named executive officers. The Company seeks your advisory vote and asks that you support the compensation of the named executive officers as disclosed in this proxy statement. Our Board intends to conduct an annual advisory vote on the compensation of the Company’s named executive officers.

As described in detail under “COMPENSATION DISCUSSION AND ANALYSIS,” our compensation program is designed to attract, retain and motivate our executives and drive overall Company performance. We believe that our compensation program, with its balance of short-term incentives and long-term incentives (including both time-based and performance-based equity awards that vest over multiple years), rewards sustained performance that is aligned with shareholder interests.

This proposal, commonly known as a “say-on-pay” proposal, gives the Company’s shareholders the opportunity to express their views on the compensation of our named executive officers. This vote is not intended to address any specific item of compensation, but rather the overall compensation of the Company’s named executive officers described in this proxy statement.

Accordingly, the Board invites you to review carefully the section titled “COMPENSATION DISCUSSION AND ANALYSIS” beginning on page 35 and the tabular and other disclosures on compensation under “2020 Executive Compensation” beginning on page 49 and to cast a vote to approve the compensation of the Company’s named executive officers through the following resolution:

“Resolved, that shareholders approve the compensation of the Company’s named executive officers, as discussed and disclosed in the Compensation Discussion and Analysis, the executive compensation tables, and any narrative executive compensation disclosure contained in this proxy statement.”

The say-on-pay vote is advisory, and therefore not binding on the Company, the Compensation Committee of the Board (the “Compensation Committee”) or the Board. The Board and Compensation Committee value the opinions of the Company’s shareholders and to the extent there is any significant vote against the named executive officers’ compensation as disclosed in this proxy statement, the Board will consider the shareholders’ concerns and the Compensation Committee will evaluate whether any actions are necessary to address those concerns.

At our 2017 Annual Meeting of Shareholders, our shareholders voted, in an advisory vote, on various frequencies for conducting future advisory votes with respect to the compensation of our named executive officers, with an annual frequency receiving the most advisory votes that were cast. After considering those voting results and other factors, our Board determined that the Company would hold an annual advisory vote on the compensation of our named executive officers until (a) the next required vote on the frequency of shareholder votes on the compensation of our named executive officers or (b) the Board otherwise determines that a different frequency for such advisory votes is in the best interests of our shareholders.

OUR BOARD RECOMMENDS

THAT YOU VOTE FOR PROPOSAL 3.

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PROPOSAL 4 — APPROVAL OF 2021 PLAN

The Board has unanimously approved the Zix Corporation 2021 Omnibus Incentive Plan (the “2021 Plan”) to replace the Zix Corporation Amended and Restated 2018 Incentive Plan (the “Prior Incentive Plan”), subject to shareholder approval at the Annual Meeting, and recommends that the Company’s shareholders approve and adopt the 2021 Plan. We intend to reserve 5,650,000 of shares of our common stock for issuance pursuant to awards under the 2021 Plan.

The Company considers the 2021 Plan an essential element of total compensation and believes the 2021 Plan promotes its interests and the interests of its shareholders by: (i) attracting and retaining the services of employees, officers, directors and consultants upon whose judgment, interest and special effort the successful conduct of the Company’s operation in largely dependent; and (ii) encouraging the active interest of those persons in the development and financial success of the Company by granting awards designed to provide participants in the 2021 Plan with proprietary interest in the growth and performance of the Company.

A total of 6,000,000 shares of our common stock were authorized for grant under the Prior Incentive Plan. As of March 31, 2021, 585,611 shares remained available for grant under the Prior Incentive Plan, as described further in the table below. See also “Compensation Discussion and Analysis— Equity Compensation Plan Information” for additional information concerning our equity compensation plan.

If our shareholders approve the 2021 Plan, it will replace the Prior Incentive Plan, such that, (i) no additional grants will be made pursuant to the Prior Incentive Plan, and (ii) any previously granted awards that are outstanding under the Prior Incentive Plan will remain outstanding in accordance with their terms. If our shareholders should fail to approve the 2021 Plan, it will not become effective and the Prior Incentive Plan will continue in force and effect. However, if the 2021 Plan is not approved by our shareholders, we may not be able to continue our equity-based long-term incentive program, and we may be required to increase the cash component of our executive compensation program in order to remain competitive and adequately compensate our employees.

Shareholder approval of the 2021 Plan would also constitute approval for purposes of satisfying the shareholder approval requirements under Section 422 of the Code so that the Compensation Committee or such other committee of our Board that may be designated to administer the 2021 Plan (the “Committee”) may grant incentive stock options, or ISOs.

Best Practices

Independent Oversight. The Committee, composed solely of independent directors, will approve all grants made under the 2021 Plan other than grants made to non-employee directors which will be approved by our Board. Additionally, the Committee may delegate to other committees of the Board, to the Chief Executive Officer and to our other senior officers its duties under the 2021 Plan pursuant to such conditions or limitations as the Committee may establish; provided, however, that such delegation will not extend to the authority to make awards to participants who are subject to Section 16 of the Exchange Act.

No Repricing of Options or SARs. The 2021 Plan prohibits repricing, replacement and regranting of stock options or stock appreciation rights (“SARs”) at lower prices unless approved by our shareholders.

No Discounted Options or SARs. Stock options and SARs may not be granted with an exercise price below the closing price of our common stock on the date of grant.

No Dividends on Options or SARs. Dividends and dividend equivalents may not be paid or accrued on stock options or SARs.

Limited Terms for Options and SARs. Stock options and SARs granted under the 2021 Plan are limited to 10-year terms.

No Liberal Share Counting with Respect to Options or SARs. Shares of our common stock that are (i) not issued or delivered as a result of the net settlement of a stock-settled SAR or option, (ii) withheld or delivered

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to satisfy the applicable withholding taxes related to an award, (iii) used to satisfy the exercise price related to an option or SAR, or (iv) repurchased on the open market with the proceeds of an option’s exercise price will not become available again for awards under the 2021 Plan.

No Dividends or Dividend Equivalents on Unvested Awards. The right to receive payment of dividends or dividend equivalents will be forfeited to the extent that an underlying award of restricted stock or restricted stock units do not vest, are forfeited or are otherwise cancelled.

Annual Limitation on Director Awards and Compensation. The aggregate grant value of awards and cash compensation paid to any individual non-employee director may not exceed $1,000,000 in any calendar year. The extent to which such awards may be granted may be further limited pursuant to the terms, conditions and parameters of a plan, program or policy for the compensation of nonemployee directors as in effect from time to time.

Clawback or Recoupment. Awards granted under the 2021 Plan will be subject to any clawback policy implemented by the Company.

No Transferability. Awards generally may not be transferred, except by will or the laws of descent and distribution or pursuant to a qualified domestic relations order, unless otherwise provided in the applicable award agreement.

No “Evergreen” Provision. Shares of our common stock authorized for issuance under the 2021 Plan will not be replenished automatically. Any additional shares to be issued over and above the amount for which we are seeking authorization must be approved by our shareholders.

No Automatic Grants. There are no automatic grants to new participants or “reload” grants when outstanding awards are exercised, expire or are forfeited.

No Tax Gross-Ups. Participants do not receive tax gross-ups under the 2021 Plan.

Information on Equity Compensation Plans as of March 31, 2021

The information included in this Proxy Statement and our 2020 Annual Report is updated by the following information regarding all existing equity compensation plans as of March 31, 2021:

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The Compensation Committee took the above information on existing equity compensation plan awards into account in setting the number of authorized shares in the proposed 2021 Plan.

Summary of the 2021 Plan

A description of the 2021 Plan is set forth below. Because the description of the 2021 Plan in this proxy statement is a summary, it may not contain all the information that may be important to you. The summary is qualified in its entirety by reference to the 2021 Plan. You should carefully read the 2021 Plan, a copy of which is attached hereto as Appendix A to this proxy statement.

Eligibility

Persons eligible for “Awards” (as defined in the 2021 Plan) are (i) all employees of the Company and its subsidiaries, (ii) non-employee directors and (iii) certain independent contractors. As of March 31, 2021, approximately 40 employees and non-employee directors would be eligible for grants of Awards under the 2021 Plan.

Shares Available for Awards

The aggregate number of shares of our common stock reserved and available for issuance pursuant to Awards granted under the 2021 Plan will be 5,650,000, all of which may be issued as incentive stock options under Section 422 of the Code. The closing price per share of our common stock on March 29, 2021 was $7.27.

Each share of our common stock subject to an Award granted under the 2021 Plan is counted against the above share reserve as one share. If an Award expires or is terminated, cancelled or forfeited, the shares associated with the expired, terminated, cancelled or forfeited Awards immediately become available for additional Awards under the 2021 Plan, it being understood that no increase or decrease in the above share reserve occurs with respect to an Award that can only be settled in cash. Moreover, the number of shares of common stock reserved for issuance under the 2021 Plan is not increased by (i) shares not issued or delivered as a result of the net settlement of a stock-settled SAR or option, (ii) shares that are withheld or delivered to satisfy the applicable withholding taxes related to an Award, (iii) shares that are used to satisfy the exercise price related to an option or SAR, and (iv) shares repurchased on the open market with the proceeds of an option’s exercise price.

Administration

The Committee administers the 2021 Plan with respect to Awards to employees and independent contractors and has broad power to take actions thereunder, to interpret the 2021 Plan and to adopt rules, regulations and guidelines for carrying out its purposes. The Board has the sole authority to grant Awards under the 2021 Plan with respect to non-employee directors. The Committee may, in its discretion, among other things: (i) extend the exercisability of an Award in a manner consistent with applicable law or (ii) accelerate the vesting of or eliminate or make less restrictive any restrictions contained in any Award, waive any restrictions or other provision of the 2021 Plan or in any Award or otherwise amend or modify any Award in a manner that is consistent with the minimum vesting periods set forth in the 2021 Plan, and, in each case, that is (x) not adverse to that participant holding the Award or (y) consented to by that participant.

Except in connection with a transaction involving the Company or its capitalization, the terms of outstanding Awards may not be amended without approval of the shareholders of the Company to (i) reduce the exercise price of outstanding options or SARs, (ii) cancel, exchange, substitute, buyout or surrender outstanding options or SARs in exchange for cash or other Awards, (iii) take any other action with respect to a stock option or SAR that would be treated as a repricing under the rules and regulations of the principal national securities exchange on which the shares of our common stock are listed or (iv) permit the grant of any stock options or SARs that contain a so-called “reload” feature under which additional stock options, SARs or other Awards are granted automatically to the participant upon exercise of the original stock option or SAR.

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The Committee also may delegate to other committees of the Board, to the Chief Executive Officer and to our other senior officers its duties under the 2021 Plan to the extent allowed by applicable law.

The Committee will determine the employees and independent contractors to receive Awards and the terms, conditions and limitations applicable to each such Award, which terms, conditions and limitations may, but need not, include continuous service with the Company, achievement of specific business objectives, attainment of specified growth rates, increases in specified indices or other comparable measures of performance.

Amendment; Termination

The Board may amend, modify, suspend or terminate the 2021 Plan for the purpose of addressing any changes in legal requirements or for any other lawful purpose, except that no amendment that would adversely affect the rights of any participant under any Award previously granted to such participant may be made without the consent of such participant unless the amendment is reasonably necessary for such Award to comply with applicable law. In addition, no amendment will be effective prior to its approval by the shareholders of the Company to the extent such approval is required pursuant to Rule 16b-3 in order to preserve the applicability of any exemption provided by such rule to any Award then outstanding (unless the holder of such Award consents) or to the extent shareholder approval is otherwise required by applicable law.

Adjustments

Depending on the transaction described below, the Board either will or may make certain adjustments, including changes to the shares of our common stock subject to outstanding Awards and shares available for grant under the 2021 Plan, in the event of any subdivision, split or consolidation of outstanding shares, any declaration of a stock dividend payable in shares, any recapitalization or capital reorganization of the Company, any consolidation or merger of the Company with another corporation or entity, any adoption by the Company of any plan of exchange affecting the common stock or any distribution to holders of common stock of securities or property (other than normal cash dividends).

Vesting

In general, a minimum vesting or restriction period of one year will apply with respect any Award (or any portion thereof) granted under the 2021 Plan; provided an Award granted to a non-employee Director may vest on the earlier of the one-year anniversary of the date of grant or the next annual meeting of the Company’s shareholders (as long as the vesting period is not less than fifty (50) weeks after the date of grant). However, the minimum vesting or restriction period may end in connection with a participant’s death or termination of employment due to disability or in connection with a Change in Control (as described and defined below) or in connection with a participant’s Employment Termination Benefits Agreement (as described under “Separation Payments and Change in Control Payments” below) or similar agreement. In addition, the minimum vesting or restriction period will not apply to up to 5% of the shares of our common stock (i.e., 300,000 shares) that are reserved for issuance under the 2021 Plan, so long as the award certificate or other contemporaneous writing as of the date of grant designates such shares as not being subject to such minimum vesting or restriction period.

Change in Control

A “Change in Control” generally occurs upon the occurrence of any of the following: (i) during any consecutive 12-month period, individuals who at the beginning of such period were members of the Board (“Incumbent Directors”) cease for any reason to constitute at least a majority thereof, unless the election of each new director was approved by a vote of at least a majority of Incumbent Directors (for purposes hereof, if an individual’s election as a director was a result of an actual or threatened election contest or proxy contest, they are not deemed an Incumbent Director); (ii) any person or group (that is unaffiliated with the Company) becomes the beneficial owner of either 30% or more of the then-outstanding shares of our common stock or securities of the Company representing 25% or more of the combined voting power; (iii) the consummation of a reorganization, merger, sale of substantially all of the Company’s assets or similar transaction, unless (x) substantially all beneficial owners of the Company prior to the transaction continue to hold more than 50% of the surviving entity’s common stock and total voting power, (y) a majority of the directors of the surviving entity are Incumbent Directors, and (z) no person or

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group (that is unaffiliated with the Company) is the beneficial owner of either 30% or more of the surviving entity’s common stock or securities of the surviving entity representing 25% or more of the total voting power.

Unless otherwise provided in the award certificate or other agreement with a participant, the treatment of a participant’s Awards in connection with a Change in Control will depend on (i) whether Awards are assumed by the surviving entity or are otherwise equitably converted or substituted in connection with the Change in Control in a manner approved by the Committee or the Board (a “Qualifying Conversion/Assumption”), and (ii) whether a participant’s employment is terminated without cause or the participant resigns for good reason within the one-year period after the effective date of the Change in Control (a “Qualifying Termination”). In the event a Qualifying Conversion/Substitution does not occur in connection with a Change in Control, then: (x) options and SARs will become fully exercisable immediately prior to the Change in Control, (y) time-based vesting requirements on outstanding Awards will be deemed to be satisfied in full immediately prior to the Change in Control, and (z) all performance-based vesting requirements on outstanding Awards will be deemed to be satisfied on a pro-rata basis at 100% of the “target” level immediately prior to the Change in Control. In the event a Qualifying Conversion/Substitution occurs in connection with a Change in Control, but a participant incurs a Qualifying Termination, then: (A) such participant’s options and SARs will become fully exercisable, (B) time-based vesting requirements on such participant’s outstanding Awards will be deemed to be satisfied in full, and (C) all performance-based vesting requirements on such participant’s outstanding Awards will be deemed to be satisfied on a pro-rata basis at 100% of the “target” level.

Clawback

Awards under the 2021 Plan will be subject to the provisions of any clawback policy either required by applicable law or otherwise implemented by the Company, which clawback policy may provide for forfeiture, repurchase and/or recoupment of Awards and amounts paid or payable pursuant to or with respect to Awards.

Awards

At the discretion of the Committee or the Board, as applicable, employees, independent contractors or non-employee directors may be granted Awards under the 2021 Plan in the form of stock options, SARs, restricted stock, restricted stock units, cash awards, performance awards, or any other right or interest relating to shares of our common stock or cash. Such Awards may be granted singly, in combination, or in tandem.

Options

Awards may be in the form of options, which are rights to purchase a specified number of shares of our common stock at a specified price not less than that of the fair market value of a share of common stock on the date of grant. An option may be either an incentive stock option (“ISO”) that is intended to comply, or a nonqualified stock option (“NSO”) that is not intended to comply, with the requirements of Section 422 of the Code; provided that independent contractors and non-employee directors cannot be awarded ISOs. The Committee will determine the participants to receive options and the terms, conditions and limitations applicable to each such option. The term of each option may not be longer than a period of 10 years from the date of grant. Except as otherwise provided in an award certificate, any option (i) that remains outstanding as of the last day of its term, (ii) has an exercise price per share that is less than the fair market value of a share of common stock as of such day and (iii) whose exercise is prohibited as of such day pursuant to the operation of the Company’s insider trading policy, will be automatically exercised (without any action on the part of the participant holding such option) by (x) foregoing the delivery of shares otherwise deliverable upon the exercise of the option in an amount sufficient to pay the exercise price of the option and (y) satisfying tax withholding obligations by withholding from the shares otherwise deliverable upon the exercise of the option using the minimum tax rate applicable to the participant.

Stock Appreciation Rights

Awards may also be in the form of SARs, which are rights to receive a payment, in cash or shares of our common stock, equal to the fair market value or other specified value of a number of shares on the rights exercise date over a specified strike price not less than the fair market value of a share of common stock on the date of grant. The term of each SAR may not be longer than a period of ten (10) years from the date of grant. Except as otherwise

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provided in an award certificate, any SAR (i) that remains outstanding as of the last day of its term, (ii) has a strike price per share that is less than the fair market value of a share of common stock as of such day and (iii) whose exercise is prohibited as of such day pursuant to the operation of the Company’s insider trading policy, will be automatically exercised (without any action on the part of the participant holding such SAR) and any tax withholding obligations will be satisfied by withholding from the cash or shares otherwise deliverable upon the exercise of the SAR using the minimum tax rate applicable to the participant.

Stock Awards

Awards may also be in the form of grants of common stock or units denominated in common stock, including restricted stock and restricted stock units (“Stock Awards”). The terms, conditions and limitations applicable to any Stock Award will be determined by the Committee. At the discretion of the Committee, the terms of a Stock Award may include rights to receive dividends or dividend equivalents, which will only be paid if the underlying shares subject to the Award vest pursuant to the terms of the Stock Award.

Cash Awards

Awards may also be in the form of grants denominated in cash. The terms, conditions and limitations applicable to any cash awards granted pursuant to the 2021 Plan will be determined by the Committee.

Performance Awards

At the discretion of the Committee, any of the above-described Awards may be made in the form of a performance award. A performance award will be paid, vested or otherwise deliverable solely on account of the attainment of one or more performance goals, either individually or in any combination, established by the Committee and specified in the award certificate.

A performance goal need not be based upon an increase or positive result under a particular business criterion and could include, for example, maintaining the status quo or limiting economic losses (measured, in each case, by reference to specific business criteria). The amount of cash or shares of our common stock payable or vested pursuant to performance awards may be adjusted upward or downward, either on a formula or discretionary basis or any combination, as the Committee determines.

Director Award Limits

No non-employee director may be granted during any calendar year Awards (in his or her capacity as a director) having a fair value determined on the date of grant when added to all cash compensation paid to the non-employee director during the same calendar year in excess of $1,000,000. The extent to which such Awards may be granted may be further limited pursuant to the terms, conditions and parameters of a plan, program or policy for the compensation of non-employee directors as in effect from time to time.

U.S. Federal Income Tax Consequences

The following is a summary of the general rules of current U.S. Federal income tax law relating to the tax treatment of Awards that may be issued under the 2021 Plan. The discussion is general in nature and does not take into account a number of considerations which may apply in light of the particular circumstances of a participant. This summary is not complete and does not attempt to describe any tax consequences arising in the context of the participant’s death or the income tax laws of any local, state or foreign country in which the participant’s income or gain may be taxable.

Stock Awards

Restricted Stock. A participant generally recognizes no taxable income at the time of an Award of restricted stock. A participant may, however, make an election under Section 83(b) of the Code to have the grant taxed as compensation income at the date of receipt, with the result that any future appreciation or depreciation in the value of the shares of stock granted may be taxed as capital gain or loss on a subsequent sale of the shares. If the

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participant does not make a Section 83(b) election, the grant will be taxed as compensation income at the full fair market value on the date the restrictions imposed on the shares expire. Unless a participant makes a Section 83(b) election, any dividends paid to the participant on the shares of restricted stock will generally be compensation income to the participant and deductible by us as compensation expense. In general, subject to the limitations discussed below, we will receive a deduction for U.S. Federal income tax purposes for any compensation income taxed to the participant. To the extent a participant realizes capital gains, as described above, we will not be entitled to any deduction for federal income tax purposes.

Restricted Stock Units. A participant who is granted restricted stock units will recognize no income upon grant of the restricted stock units. At the time the underlying shares of common stock (or cash in lieu thereof) are delivered to a participant, the participant will recognize compensation income equal to the full fair market value of the shares received. Subject to the limitations discussed below, we will generally be entitled to a deduction for U.S. Federal income tax purposes that corresponds to the compensation income recognized by the participant.

Options; Stock Appreciation Rights

Options granted under the 2021 Plan may constitute ISOs within the meaning of Section 422 of the Code, while other options granted under the 2021 Plan may constitute NSOs. Grants of options to non-employee directors and independent contractors are NSOs. The Code provides for tax treatment of options qualifying as ISOs that may be more favorable to participants than the tax treatment accorded NSOs. Generally, upon the grant or exercise of an ISO, the optionee will recognize no taxable income for U.S. Federal income tax purposes, although the difference between the exercise price of the ISO and the fair market value of the stock at the date of exercise is an addition to income in determining alternative minimum taxable income and such amount may be sufficient in amount to subject the optionee to the alternative minimum tax. On the sale of shares acquired by exercise of an ISO (assuming that the sale does not occur within two years of the grant date or within one year of the exercise date), any gain will be taxed to the optionee as long-term capital gain. Except with respect to death or disability, an optionee has three months after termination of employment in which to exercise an ISO and retain favorable tax treatment at exercise. No deduction is available to the Company upon the grant or exercise of an ISO (although a deduction may be available if the participant disposes of the shares so purchased before the applicable holding periods expire).

In contrast, upon the exercise of an NSO, the optionee recognizes ordinary taxable income on the exercise date in an amount equal to the excess of the fair market value of the shares purchased over the exercise price. Upon the sale of such shares by the optionee, any difference between the fair market value at the date of sale and the fair market value at the date of exercise will be treated generally as capital gain or loss. Subject to the limitations discussed below, upon exercise of an NSO, the Company is entitled to a tax deduction in an amount equal to the ordinary taxable income recognized by the participant.

Participants do not recognize taxable income upon the grant of a SAR. Upon the exercise of a SAR, the participant will recognize ordinary income in an amount equal to the cash or fair market value of the shares received at the date of exercise of the SAR. The participant’s tax basis in any shares received on the exercise of a SAR will generally equal the fair market value of such shares on the date of exercise. Subject to the limitations discussed below, the Company will be entitled to a deduction for U.S. Federal income tax purposes that corresponds as to timing and amount with the taxable income recognized by the participant under the foregoing rules.

Deductibility; Excise Taxes

Code Section 162(m). In general, a U.S. Federal income tax deduction is allowed to the Company in an amount equal to the ordinary taxable income recognized by a participant with respect to Awards granted under the 2021 Plan, provided that such amount constitutes an ordinary and necessary business expense of the Company, that such amount is reasonable and that the Company satisfies any withholding obligations with respect to the participant’s ordinary taxable income. Following the enactment of the Tax Cuts and Jobs Act, beginning with the 2018 calendar year, the $1 million annual deduction limitation under Section 162(m) applies to compensation paid to any individual who serves as the Chief Executive Officer, Chief Financial Officer or qualifies as one of the other three most highly compensated executive officers in 2017 or any later calendar year. See also “Compensation Discussion and Analysis— Impact of Accounting and Tax Treatments of Compensation” for a more robust discussion of Section 162(m) of the Internal Revenue Code.

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Change in Control. The acceleration of the exercisability or the vesting of an Award upon the occurrence of a change in control may result in an “excess parachute payment” within the meaning of Section 280G of the Code. A “parachute payment” occurs when an employee receives payments contingent upon a change in control that exceed an amount equal to three times his or her “base amount.” The term “base amount” generally means the average annual compensation paid to such employee during the five calendar years preceding calendar year in which the change in control occurs. An “excess parachute payment” is the excess of all parachute payments made to the employee on account of a change in control over the employee’s base amount. If any amount received by an employee is characterized as an excess parachute payment, the employee is subject to a 20% excise tax on the amount of the excess, and the Company is denied a tax deduction with respect to such excess.

Code Section 409A. Section 409A of the Code generally provides that any deferred compensation arrangement must satisfy specific requirements, both in operation and in form, regarding (i) the timing of payment, (ii) the advance election of deferrals, and (iii) restrictions on the acceleration of payment. Failure to comply with Section 409A of the Code may result in the early taxation (plus interest) to the participant of deferred compensation and the imposition of a 20% penalty on the participant on such deferred amounts included in the participant’s taxable income. The Company intends to structure Awards under the 2021 Plan in a manner that is designed to be exempt from or comply with Section  409A of the Code.

Future Benefits Under the 2021 Plan

As part of its regular annual process of granting equity awards to its officers and employees, in March of 2021, the Company opted to make grants under the 2021 Plan that are contingent on approval of that Plan by shareholders of the Company at its 2021 annual meeting. This decision was due in part to a shortage of available shares for grants under the Prior Incentive Plan. The contingent grants consisted of both time-based and performance-based RSUs covering an aggregate of 408,152 shares (assuming target performance for the performance-based awards). See the New Plan Benefits Table (below) for more information. Other than these previously granted contingent awards, it is not possible to determine the benefits that will be received in the future by participants in the 2021 Plan or the benefits that would have been received by such participants if the 2021 Plan had been in effect in the year ended December 31, 2020. Certain tables in this proxy statement set forth information with respect to prior awards granted to our named executive officers under the Prior Incentive Plan, which remains in effect.

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In 2021, the Company currently expects to award each non-employee director restricted stock units as described in more detail under “Director Compensation.” Because future Awards are in the discretion of the Board and the Committee, the number of shares subject to future Awards could increase or decrease and the type and terms of future Awards could change as well, all without the need for future shareholder approval.

The Board believes that the approval of the 2021 Plan is in the best interest of the Company and its shareholders. The Board therefore recommends a vote for the 2021 Plan, and it is intended that the proxies not marked to the contrary will be so voted. Because approval of the 2021 Plan will increase the number of shares available for issuance to all directors and executive officers of the Company, each of the directors and executive officers of the Company has an interest and may benefit from the approval of the 2021 Plan.

OUR BOARD RECOMMENDS

THAT YOU VOTE FOR PROPOSAL 4

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Mark J. Bonney joined our Board in January 2013. He currently serves as President and CEO of On Board Advisors, LLC, a financial and strategic advisory firm. Since July 2020, Mr. Bonney has been a member of the Board of Directors of Title Shop Holdings, Inc., a specialty retailer of natural stone, man-made tile and related materials. From October 2019 to December 2019 Mr. Bonney was independent Chair of the Board of SeaChange International, Inc., (NASDAQ: SEAC), a provider of end-to-end video delivery and management software solutions for cable wireless, OTT and other content providing enterprises. From April 2019 to October 2019 he was Executive Chair and Principal Executive Officer of SeaChange. From August 2017 to April 2019 he was a Director and Chair of the Audit and Compensation Committees of SeaChange. From May 2018 until its merger with Taptica, PLC in April 2019, he served as President and Chief Executive Officer and a director of RhythmOne PLC, (LSE AIM:RTHM), a provider of digital advertising solutions. Until its sale in August 2017, he served as President and Chief Executive Officer and a director of MRV Communications, Inc., a supplier of network equipment to the telecommunications industry. Mr. Bonney served as an independent Director and Chair of the Audit Committee of MRV from April 2013 until joining the management team in August 2014. He also served as a Director and Chair of the Audit Committee and the Corporate Governance and Nominating Committee of Sigma Designs, Inc., (NASDAQ:SIGM), a provider of high-performance system-on-a-chip semiconductor solutions enabling the convergence of the smart home, from August 2012 through August 2015. He was executive vice president and Chief Financial Officer of Direct Brands, LLC, a privately owned direct to consumer media company from 2010 to 2012, vice president and general manager of the Authentication Solutions Group of JDS Uniphase Corporation (“JDSU”) an optical technologies and telecommunications firm, from 2008 to 2010 and executive vice president and Chief Financial Officer of American Bank Note Holographics, Inc., (“ABNH”) an optical security device company from 2005 to 2008, before the company’s sale to JDSU. Mr. Bonney also served as an outside director and Chair of the audit committee of ABNH from 2003 until 2005. Mr. Bonney has also held executive roles with technology companies, including president, Chief Operating Officer and a director of Axsys Technologies, Inc., a manufacturer of components and subsystems for aerospace, defense, data storage, medical and other high technology applications from 1999 to 2002 and Chief Financial Officer of Zygo Corporation, a manufacturer of metrology measurement and control systems and optical components for semiconductor, data storage and industrial markets from 1993 to 1999. He received a Master’s degree from the University of Hartford and a Bachelor’s degree from Central Connecticut State University.

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Our Board selected Mr. Bonney to serve as a director because of his experience as a Chief Executive Officer, Chief Operating Officer and a Chief Financial Officer of several middle market publicly-traded companies. This experience and his experience as a director of seven publicly traded technology companies allow Mr. Bonney to contribute to the Board’s deliberations across a broad array of issues as well as providing the Board with meaningful experience in discharging its oversight of corporate governance, operations and financial performance.

Marcy Campbell was elected to our Board in March 2020. Ms. Campbell is currently Vice President – Global Professional Services, Digital & In-Store Commerce, SME Sales for PayPal. Prior to this role, she held roles as Vice President and General Manager North America, Vice President Worldwide Sales & Accounts for Braintree (a PayPal Division) and Vice President North American Sales and Accounts for Braintree. Ms. Campbell has led high-performance sales, business development, and marketing organizations for large and small enterprises including Qubole, Engine Yard, Netscape, and IBM. Ms. Campbell holds a Bachelors of Arts in History and Communications from the University of Hartford, where she was summa cum laude, and a National Regent Scholar.

Our Board selected Ms. Campbell to serve as a director because of her experience at technology companies experiencing rapid growth, which contributes to the Board’s growth strategy and customer success organization. She brings over 25 years of experience in building and managing sales, marketing, business development and service operations in global information technology businesses.

Taher A. Elgamal was elected to our Board in July 2011. Dr. Elgamal currently serves as Chief Technology Officer Security at Salesforce.com, Inc., a provider of enterprise cloud computing solutions. He is also co-founder and Chair of IdentityMind, Inc. and serves as a director of Intelligent Fiber Optic Systems Corporation and Vindicia, Inc. Dr. Elgamal has also held executive roles at technology and security companies, including as Chief Executive Officer of First Information Security (data security) from 2012 to 2013, Chief Security Officer of Axway, Inc. (data security) from 2008 to 2011, Chief Technology Officer of Tumbleweed Communications (email encryption) from 2006 to 2008, Chief Technology Officer of Securify, Inc. from 2001 to 2004, Chief Executive Officer and President of Securify, Inc. from 1998 to 2001 and chief scientist of Netscape Communications from 1995 to 1998. Dr. Elgamal is a recipient of the RSA Conference 2009 Lifetime Achievement Award, and he is recognized as the “father of SSL,” the Internet security standard Secure Sockets Layer. Dr. Elgamal was issued several patents in online security, payments and data compression. He received a Bachelor’s degree in electrical engineering from Cairo University, a Master’s degree in electrical engineering from Stanford University and a doctorate in electrical engineering from Stanford University.

Our Board selected Dr. Elgamal to serve as a director because of his expertise in cybersecurity and encryption technologies. In addition, his experience working with data security firms contributes to the Board’s oversight of the Company’s cybersecurity risks as well as its marketing strategy. His experience as an executive and director at public and private information technology companies adds to the Board’s understanding of many matters facing the Company, including personnel management, business operations and corporate governance.

James H. Greene, Jr. joined our Board in February 2019. Mr. Greene is a Founding Partner of True Wind Capital Management, L.P. (“True Wind”), a private equity fund manager focused on the technology industry, where he serves on the Investment Committee and is responsible for all aspects of managing the firm. Prior to founding True Wind in 2015, Mr. Greene was with Kohlberg Kravis Roberts & Co. (“KKR”), a global investment manager, which he joined in 1986. At KKR, Mr. Greene founded the Global Technology Group in 2004 and led the Group until 2010. Mr. Greene headed the Industrial Group at KKR until 2013. Mr. Greene became a Partner at KKR in 1993, a Member in 1996, and an Advisory Partner in 2013. Prior to joining KKR, Mr. Greene had 14 years of banking experience as a Vice President at Bankers Trust Company. Mr. Greene currently serves as Chair of Pegasus TransTech (“Transflo”), and is a director of Western New York Energy LLC and of Sysnet Global Solutions. Mr. Greene also serves as Chair of TWC Tech Holdings II Corp; Chair of Nebula Caravel Acquisition Corp.; Chief Executive Officer, Chair and a director of Bilander Acquisition Corp., Brigantine Acquisition Corp., Galliot Acquisition Corp., and Mistico Acquisition Corp. He is an Emeritus Trustee of the University of Pennsylvania, a member of the Executive Committee and Board of Penn Medicine, which includes the Perelman School of Medicine and the University of Pennsylvania Health System. Mr. Greene received a Bachelor’s degree in Economics from the University of Pennsylvania.

Our Board selected Mr. Greene to serve as a director in connection with the $100 million private placement that we consummated with True Wind in February 2019 and pursuant to the Investment Agreement (the “Investment Agreement”) between us and True Wind, dated January 14, 2019, which we entered into with respect to that

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transaction. Mr. Greene’s experience as a private equity investor in the information technology industry brings to the Board valuable experience and perspective on a variety of matters facing the Company, including financial and capital markets, operations, business development, personnel management and executive compensation.

Robert C. Hausmann was elected to our Board in November 2005, was elected Lead Independent Director in December 2012 and non-executive Chair of the Board in December 2014. In September 2016, Mr. Hausmann became an Operating Partner with Thoma Bravo, a private equity investment firm. During varying periods from 2016 to the present time, Mr. Hausmann has served the following Thoma Bravo-affiliated companies (all of which are privately held) in the following capacities: Veriforce formerly known as PEC Safety (chair of board, chair of compensation committee and member of audit committee); Nixtex Global, Ltd. (member of board, audit and compensation committees); Motus, LLC (member of board and audit committee); Riskonnect, Inc. (member of board and audit committee); and T2 Systems, Inc. (member of board and audit committee). Mr. Hausmann was co-founder, a director and Chief Financial Officer of TetraSun, Inc., a solar cell R&D and Manufacturing company that was sold to First Solar, Inc. in 2013. Prior to co-founding TetraSun, Mr. Hausmann was a consultant to public and private companies with respect to operational and financial management matters, including Sarbanes-Oxley and systems and process re-engineering. He also served as Vice President and Chief Financial Officer of Securify, Inc. (computer security monitoring) from September 2002 through June 2005. From September 1999 through September 2002, Mr. Hausmann served as Vice President and Chief Financial Officer of Resonate, Inc. (network traffic management) and managed that company’s initial public offering. Prior to these positions, he served as Operations Partner and Chief Financial Officer of Mohr, Davidow Ventures, a Silicon Valley-based venture capital partnership; and as the Chief Financial Officer of Red Brick Systems, Inc., where Mr. Hausmann managed the company’s initial public offering. Mr. Hausmann earned a Master of Business Administration degree from Santa Clara University and a Bachelors of Arts degree in Finance and Accounting from Bethel University.

Our Board selected Mr. Hausmann to serve as a director because of his experience as Operating Partner of a technology oriented private equity investment firm, Chief Financial Officer of two publicly-traded companies and two private companies and as Chief Financial Officer of a Silicon Valley venture capital firm, all of which contributes to the Board’s resources in overseeing the Company’s financial and accounting matters, including public company reporting and disclosure. His consulting work at public and private companies, principally in the information technology industry, brings to the Board valuable experience and perspective on a variety of matters facing the Company, including financial markets, operations, corporate governance, compliance and systems and process re-engineering.

Maribess L. Miller was elected to our Board in April 2010. Ms. Miller was a member of the public accounting firm PricewaterhouseCoopers LLP from 1975 until 2009, including serving as the North Texas Market Managing Partner from 2001 until 2009; as Southwest Region Consumer, Industrial Products and Services Leader from 1998 until 2001; and as Managing Partner of that firm’s U.S. Healthcare Audit Practice from 1995 to 1998. Since July 2014, Ms. Miller has served as a member of the board of directors for Triumph Bancorp, Inc. (NASDAQ: TBK) and is currently chair of the Nominating and Corporate Governance committee and member of the audit committee. Ms. Miller serves on the board of D.R. Horton where she chairs the nominating governance committee and sits on the compensation and audit committees. Ms. Miller is also a member of the board of directors and chair of the audit committee for Midmark Corporation, a privately-held medical supply company. She served on the Texas State Board of Public Accountancy from 2009 until 2015, is past Board Chair for the Texas Health Institute and the North Texas Chapter of the National Association of Corporate Directors. She also served on the board of the TCU Neeley School of Business. She graduated cum laude with a Bachelor’s degree in Accounting from Texas Christian University. Ms. Miller is a retired Certified Public Accountant.

Our Board selected Ms. Miller to serve as a director because of her extensive experience in auditing and consulting with companies in various fields, including healthcare and technology companies, which allows her to contribute valuable perspective and insights about the Company’s operations. In addition, Ms. Miller has special expertise in public company accounting and financial reporting. She brings to our Board and the Audit Committee invaluable technical understanding of public company accounting and internal control over financial reporting.

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Brandon Van Buren joined our Board in February 2019. Mr. Van Buren is a Partner at True Wind Capital, a private equity fund manager focused on the technology industry, which he joined in 2017 and where he serves on the Investment Committee. From 2014 to 2017, Mr. Van Buren was a Principal at Google Capital, the private investment arm of Alphabet Inc., where he led growth equity investments within the technology, media, and telecommunications sectors. Prior to joining Google Capital, Mr. Van Buren was with KKR, a global investment manager, from 2010 to 2012 where he executed leveraged buyout transactions within the technology space. Mr. Van Buren currently serves as a director of Open Lending (NASDAQ: LPRO), a lending enablement platform for the automotive finance market, since 2020, as a director of TWC Tech Holdings II Corp. (NASDAQ: TWCT), a special purpose acquisition company, since November 2020, as a director of Nebula Caravel Acquisition Corp. (NASDAQ: NEBC), a special purpose acquisition company, since December 2020, as a director of Bilander Acquisition Corp. (NASDAQ: TWCB) since February 2021, as a director of Galliot Acquisition Corp. (NASDAQ: TWCG) since February 2021, as a director of Mistico Acquisition Corp. (NASDAQ: TWCM) since March 2021, and as a director of Brigantine Acquisition Corp. (NASDAQ: BRIG) since March 2021. Mr. Van Buren holds a B.S. in Business Administration with concentrations in Finance and Accounting from California Polytechnic State University, San Luis Obispo and an M.B.A. from Harvard Business School, where he was a Baker Scholar.

Our Board selected Mr. Van Buren to serve as a director in connection with the $100 million private placement that we consummated with True Wind in February 2019 and pursuant to the Investment Agreement entered into with respect to that transaction. Mr. Van Buren’s experience as a private equity investor in the information technology industry brings to the Board valuable experience and perspective on a variety of matters facing the Company, including financial and capital markets, operations, business development, finance and mergers and acquisitions.

David J. Wagner was elected to our Board in January 2016. He joined our Company in January 2016 as President and CEO. Prior to joining the Company, Mr. Wagner held leadership roles at Entrust for 20 years. From 2013 through 2015, Mr. Wagner served as President of Entrust, where he led the successful integration of Entrust after its acquisition by Datacard. Mr. Wagner delivered revenue growth and led the re-investment strategy to move Entrust solutions to the cloud. He also served as Chief Financial Officer of Entrust from 2003 to 2013. Before joining Entrust, Mr. Wagner held various finance and accounting positions at Nortel Networks from 1991 through 1995 and at Raytheon Systems from 1986 to 1991. Mr. Wagner is a graduate of The Pennsylvania State University where he received an undergraduate degree in accounting and a Master of Business Administration.

Our Board selected Mr. Wagner to serve as a director because, as the Company’s CEO, his direct, day-to-day knowledge of and interaction with all aspects of our business, including shareholders, employees and customers, is unique among the directors and provides our Board with important insights into our Company’s business. In addition, he brings his sales, marketing and strategy development and implementation experience gained through his executive experience in the global security industry.

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For biographical information regarding David J. Wagner, please see “— Directors” above.

Ryan L. Allphin joined Zix in November 2020 and serves as Chief Product Officer where he leads all Product and Technology. Mr. Allphin brings over 25 years of experience in building and delivering traditional and cloud-based, enterprise-grade networking, cybersecurity and data intelligence technology solutions. Prior to his role at Zix, Mr. Allphin served in several leadership roles including 14 years in cybersecurity working at McAfee. While at McAfee, he led the Security Management business unit as SVP & GM where he expanded the business through organic and inorganic innovation and double-digit growth. Mr. Allphin has a wide range of experience in product and business strategy, customer engagement and technology innovation. He is a graduate of Utah Valley University where he received a computer science degree.

John P. Di Leo joined Zix in December 2019 and serves as Chief Revenue Officer. Before joining Zix, Mr. Di Leo held the role of president at Broad Pointe Consulting from 2016 to 2019. Previously he was SVP/Chief Revenue Officer for Entrust Datacard for nearly 7 years, and held executive management positions spanning a 25 year career at NCR Corporation including Region Vice President/GM – North American and VP Global Services Sales, Marketing and Product Management. He has a Master of Science in Business from The Johns Hopkins University – Carey Business School.

David E. Rockvam has served as our Chief Financial Officer (“CFO”) since June 27, 2016. Mr. Rockvam brings a wealth of experience in the data security market and more than 20 years of experience in investor relations, financial planning, and business and corporate development. Prior to his role at Zix, he served in several executive roles during 18 years with Entrust, including Chief Investor Relations Officer and Chief Financial Officer of Asia Digital Media, an Entrust joint venture. He also held executive roles at Entrust such as General Manager of Entrust Certificate Services, Chief Marketing Officer, and Senior Vice President of Product Marketing. Mr. Rockvam began his career at Nortel Networks, where he served in various financial leadership positions. He earned a Master of Business Administration from The University of Texas at Dallas and an undergraduate degree from Texas Tech University.

Noah F. Webster has served as our Chief Legal & Compliance Officer since October 2020, formerly Vice President and General Counsel since June 2018. Mr. Webster has over 17 years of legal experience in negotiating agreements, security, compliance and intellectual property. Prior to joining Zix, Mr. Webster worked for eight years at BlackBerry, serving most recently as General Counsel, Mobility Solutions, and holding other legal roles involving privacy and anticorruption legal compliance, M&A, and patent litigation. Before BlackBerry, Mr. Webster worked for Kirkland & Ellis in Chicago, where he represented and advised clients in patent litigations, trademark infringement and general intellectual property matters. Mr. Webster earned his Juris Doctorate degree from the University of Illinois College of Law and clerked with the U.S. District Court for the Eastern District of Michigan and the High Court of American Samoa. He began his career serving as a U.S. Army Engineer Officer. He is a graduate of the U.S. Military Academy, where he earned an undergraduate degree in mechanical engineering. Mr. Webster is a member of the bar for the states of Texas and Illinois. He also holds certification as a Leading Professional in Ethics & Compliance and is registered to practice before the United States Patent and Trademark Office.

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