EXHIBIT 32.2


                                  CERTIFICATION
                       PURSUANT TO 18 U.S.C. SECTION 1350,
      AS ADOPTED PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


         In connection with the Annual Report on Form 10-K of Zix Corporation
(the "Company") for the year ended December 31, 2003 as filed with the
Securities and Exchange Commission on the date hereof (the "Report"), I, Steve
M. York, Senior Vice President, Chief Financial Officer and Treasurer of the
Company, certify to the best of my knowledge and in my capacity as an officer of
the Company, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section
906 of the Sarbanes-Oxley Act of 2002, that:

     1.   The Report fully complies with the requirements of Section 13(a) or
          15(d) of the Securities Exchange Act of 1934, as amended; and

     2.   The information contained in the Report fairly presents, in all
          material respects, the financial condition and results of operations
          of the Company as of the dates and for the periods expressed in the
          Report.

Date:  March 15, 2004


                                                /s/Steve M. York
                                        ---------------------------------------
                                                   Steve M. York
                                        Senior Vice President, Chief Financial
                                                Officer and Treasurer