DOCUMENT:Q166654  24-AUG-2001  [exchange]
TITLE   :XFOR: Message Loop Across Two Mail Systems
PRODUCT :Microsoft Exchange
PROD/VER::4.0,5.0,5.5
OPER/SYS:
KEYWORDS:kbtshoot kbusage exc4 exc5 exc55

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The information in this article applies to:

 - Microsoft Exchange Server, versions 4.0, 5.0, 5.5 
 - Microsoft Exchange 2000 Server 
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SYMPTOMS
========

A Microsoft Exchange Server distribution list (DL) may contain recipients that
exist on both sides of a connector (for example, on a TAO host and in Exchange
Server). If dirsync is enabled and propagation of DLs is allowed, the Exchange
Server DL shows up in the foreign mail system, usually as an individual
recipient within the foreign mail system. If a user on the foreign mail system
sends a message to that DL, the DL traverses the connector and be fanned out at
the DL's creation point (in this case Exchange Server).

Once DL expansion is completed, Exchange Server attempts to send to all
recipients. If one or more of these recipients reside on the foreign mail
system, then when Exchange Server attempts to send to these recipients, the
connector recognizes that the correlation ID of this message is the same as that
of the original message (original DL). The connector detects this as a looping
message and a corresponding log entry is written. This is because each message
that traverses the connector has a unique correlation ID. During message
conversion this ID is extracted and appended to the correlation table. If two
instances of a message traverse the connector with the same correlation ID, the
connector attributes this to a looping message.

RESOLUTION
==========

To resolve this problem:

 - In order to modify the default behavior of message-looping detection, add the
   following parameter to the [LME] section of the Linkage.ini or Exchconn.ini
   files:

         DISABLETRACECHECKEX = YES

CAUTION: Use this modification with caution. This parameter also disables all
messages-looping protection that Exchange Development Kit (EDK) connectors
provide as an important feature.

The Disabletracecheckex parameter is valid for all EDK connectors, which includes
the following:

 - Microsoft Exchange Connector for Lotus Notes

 - Microsoft Exchange Connector for GroupWise

 - Microsoft Exchange Connector for IBM OfficeVision/VM (Exchange 5.5 ONLY)

 - Microsoft Exchnage Connector for SNADS (Exchange 5.5 ONLY)

STATUS
======

This behavior is by design.

Additional query words:

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Keywords          : kbtshoot kbusage exc4 exc5 exc55 
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbExchange400 kbZNotKeyword2
Version           : :4.0,5.0,5.5
Issue type        : kbprb

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