The explanation I got from Cisco is that Exchange 5.x / 2000 implements a superset of ESMTP commands. In fact with the fixup SMTP turned on the PIX only listens to seven SMTP commands and ignores all ESMTP commands. With the fixup SMTP turned off, it should allow most if not all SMTP packets to flow untouched. The issue seems to be that the Exchange server insists upon trying to use ESMTP for certain functions and may under certain circumstances refuse to renegotiate and fall back to SMTP, when ESMTP commands are blocked or not supproted.
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Gregg Rosenberg - N9NNO RICIS, Inc.
Chief Technology Officer 708-444-2690 Voice
[EMAIL PROTECTED] 708-444-2697 Fax
http://www.ricis.com - 866-RICIS-77 Toll Free
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