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                                                                   EXHIBIT 10.16


                     AMENDMENT NO. 3 TO EMPLOYMENT AGREEMENT

This Amendment No. 3 to Employment Agreement (this "Amendment") is made and
entered into by and between FTP Software, Inc., a Massachusetts corporation (the
"Company"), and Peter R. Simkin ("Employee"), effective as of the 19th day of
June, 1997.

WHEREAS, the Company and Employee have entered into an Employment Agreement
dated as of the Effective Time (as defined in that certain Amended and Restated
Agreement and Plan of Merger, dated as of May 21, 1996, among the Company,
Firefox Acquisition Corp. and Firefox Communications Inc.), as amended by
Amendment No. 1 to Employment Agreement effective as of August 22, 1996 and
Amendment No. 2 to Employment Agreement effective as of December 15, 1996 (as so
amended, the "Agreement"); and

WHEREAS, the Company and Employee desire to further amend the Agreement to
extend the term thereof;

NOW, THEREFORE, in consideration of the premises and for other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereby agree as follows:

1. EXTENSION OF TERM. The term of the Agreement is hereby extended to September
30, 1997. From and after the date hereof, the term "Term" as used in the
Agreement shall mean the period beginning at the Effective Time and ending on
September 30, 1997.

2. EFFECT ON AGREEMENT. Except as specifically amended hereby, the Agreement
shall continue in full force and effect.

IN WITNESS WHEREOF, this Amendment has been executed as a sealed instrument by
the Company, by its duly authorized representative, and by Employee, effective
as of the date first above written.

EMPLOYEE:                         FTP SOFTWARE, INC.         
                                   
                                   
/s/ PETER R. SIMKIN               By: /s/ GLENN C. HAZARD
- -----------------------------         -------------------------------------
Peter R. Simkin                       Glenn C. Hazard
                                      President and Chief Executive Officer