Open Text (OTEX) 10-Q 2007 Q3 Quarterly report

Exhibit 32.1

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 Quarterly Report on Form 10-Q of Open Text Corporation (the “Company”) for the quarter ended March 31, 2007 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), I, John Shackleton, President and Chief Executive Officer of the Company, certify, pursuant to 18 U.S.C. (S) 1350, as adopted pursuant to (S) 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.

/s/ JOHN SHACKLETON

John Shackleton

President and Chief Executive Officer

Dated: May 7, 2007