DOCUMENT:Q164836  08-JAN-2000  [exchange]
TITLE   :XCON: Conditional Reroute on Single Link Bounces Back
PRODUCT :Microsoft Exchange
PROD/VER:winnt:4.0
OPER/SYS:
KEYWORDS:kbusage

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The information in this article applies to:

 - Microsoft Exchange Server, version 4.0 
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SYMPTOMS
========


When messages are received from foreign X.400 systems, sometimes the messages
cannot be resolved against the Directory Service (DS). These messages are marked
as rerouted and sent back to the foreign X.400 system.

This then starts a ping-pong effect between the two systems.

CAUSE
=====

Some X.400 systems cannot handle the fact that the message is marked as REROUTED
up the same link as the message was sent. Because they cannot loop detect the
message, they consequently resend the message back to Microsoft Exchange,
starting the ping-pong effect.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Exchange version 4.0.
This problem was corrected in the latest Microsoft Exchange 4.0 U.S. Service
Pack. For information on obtaining the service pack, query on the following word
in the Microsoft Knowledge Base:

   " SERVPACK " (without the quotation marks)

Additional query words:

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Keywords          : kbusage 
Technology        : kbExchangeSearch kbExchange400 kbZNotKeyword2
Version           : winnt:4.0
Issue type        : kbbug
Solution Type     : kbfix

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