TABLE OF CONTENTS

	Page
SUMMARY TERM SHEET		i
INTRODUCTION		1
THE TENDER OFFER		5
1. Terms of the Offer		5
2. Acceptance for Payment and Payment for Shares		7
3. Procedures for Tendering Shares		8
4. Withdrawal Rights		11
5. Certain United States Federal Income Tax Consequences of the Offer and the Merger		10
6. Price Range of Shares; Dividends		13
7. Certain Effects of the Offer and the Merger		14
8. Certain Information Concerning Zix		14
9. Certain Information Concerning Purchaser and OpenText		16
10. Background of the Offer; Contacts with Zix		17
11. Purpose of the Offer and Plans for Zix; The Merger Agreement and Other Agreements		20
12. Source and Amount of Funds		45
13. Conditions to the Offer		45
14. Dividends and Distributions		46
15. Certain Legal Matters		46
16. Fees and Expenses		50
17. Miscellaneous		50
SCHEDULE A		A-1