DOCUMENT:Q190366  18-DEC-1999  [exchange]
TITLE   :XFOR: Cannot Reply to Messages Through a Cisco PIX Firewall
PRODUCT :Microsoft Exchange
PROD/VER:winnt:5.0,5.5
OPER/SYS:
KEYWORDS:exc5 exc55

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The information in this article applies to:

 - Microsoft Exchange Server, versions 5.0, 5.5 
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SYMPTOMS
========

If you send a message from one Microsoft Exchange Server computer to another
through the Internet Mail Service, and then attempt to reply to the message, the
reply may not be sent successfully. This problem occurs when the two servers are
connected through a Cisco PIX Firewall on which the Mail Guard feature is
enabled.


WORKAROUND
==========

To work around this problem, disable the Mail Guard feature on the Cisco PIX
Firewall. For additional information, contact Cisco.

For information about how to contact Cisco, query in the Knowledge Base for one
of the following articles:

   Q65416 Hardware and Software Third-Party Vendor Contact List, A-K

   Q60781 Hardware and Software Third-Party Vendor Contact List, L-P

   Q60782 Hardware and Software Third-Party Vendor Contact List, Q-Z


MORE INFORMATION
================

Mail Guard is a feature that allows messages to be transferred directly to an
internal e-mail host, eliminating the need for an e-mail relay host. Mail Guard
allows connections to an internal e-mail host through Transport Control Protocol
(TCP) port 25 only. It logs all Simple Mail Transfer Protocol (SMTP) activity
and allows only the minimum SMTP server commands found in Request for Comments
(RFC) 821, Section 4.5.1.

PIX Firewalls are manufactured by Cisco, a vendor independent of Microsoft; we
make no warranty, implied or otherwise, regarding these products' performance or
reliability.

Additional query words:

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Keywords          : exc5 exc55 
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbZNotKeyword2
Version           : winnt:5.0,5.5
Issue type        : kbprb

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