FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL OMB Number: 3235-0287 Expires: January 31, 2005 Estimated average burden hours per response... 0.5

(Print or Type Responses)

1. Name and Address of Reporting Person * ROBERTSON DAVE   2. Issuer Name and Ticker or Trading Symbol ZIX CORP [ZIXI] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner __X__ Officer (give title below) _____ Other (specify below) Vice President (Last) (First) (Middle) 2711 N. HASKELL AVENUE, SUITE 2200, LB 36 3. Date of Earliest Transaction (Month/Day/Year) 02/18/2018 (Street) DALLAS, TX 75204 4. If Amendment, Date Original Filed(Month/Day/Year) 02/22/2018 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/18/2018   F   1,977 D $ 4.16 128,340 D   Common Stock 02/19/2018   M   6,667 A (1) 135,007 D   Common Stock 02/19/2018   F   1,924 D $ 4.16 133,083 D   Common Stock 02/20/2018   F   812 D $ 4.1 132,271 D   Common Stock 02/20/2018   F   1,624 D $ 4.1 130,647 D   Common Stock 02/20/2018   M   6,666 A (1) 137,313 D   Common Stock 02/20/2018   F   1,564 (2) D $ 4.1 135,749 D   Common Stock 02/20/2018   F   2,345 D $ 4.1 133,404 D

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
	Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB control number.		SEC 1474 (9-02)

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code (Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Underlying Securities (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Restricted Stock Units

(1)

02/19/2018

M

6,667

(2)

(2)

Common Stock

6,667

$ 0

266,666 (3)

D

Restricted Stock Units

(1)

02/20/2018

M

6,666

(2)

(2)

Common Stock

6,666

$ 0

260,000 (3)

D

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
ROBERTSON DAVE 2711 N. HASKELL AVENUE SUITE 2200, LB 36 DALLAS, TX 75204			Vice President

Signatures

/s/ Noah F. Webster, Attorney-in-Fact		08/23/2018
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 4(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	Each restricted stock unit ("RSU") coverts into a share of common stock on a one-for-one basis.
(2)	Granted under the Amended and Restated 2012 Incentive Plan (as amended, the "Plan") on February 19, 2015. The 40,000 RSU grant consists of 50% RSUs that will vest pro-rata over 3 years and 50% that will vest pro-rata up to 1/3 each year the Company meets approved performance goals in 2015-2017, subject to acceleration under conditions described in the Plan.
(3)	This Form 4/A amends the Form 4 filed by the Reporting Person on February 22, 2018. The amount of securities directly beneficially owned by the Reporting Person has been historically reported incorrectly and the resulting amount of derivative securities beneficially owned following each of the transactions set for in Table II should have been reported as set forth in column 9 of Table II of this Form 4/A.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.