XCON: X.400 MTA Logs "Loop Detected" Error Message When Receiving a Message from Exchange Server

• Microsoft Exchange Server, version 5.5

SYMPTOMS

In some cases, a third-party X.400 message transfer agent (MTA) may log an error message similar to "Loop detected" when it receives a message from Exchange Server. The originator of the message will receive a non-delivery report (NDR).

This behavior only occurs under very specific circumstances:

• A message is sent from Exchange Server using the X.400 Connector. The recipients in the message are taken from the user's Personal Address Book (PAB) or are one-off addresses. At the same time, custom recipients exist for these addresses in the Exchange Server global address list.



• The message may contain multiple trace records in the X.400 P1 message header, which are marked as "rerouted." This may cause the receiving MTA to think there is a message loop.



• The number of trace records in the P1 message header depends on the number of recipients addressed. For example, if the message was sent to three recipients, there will be three trace records.

RESOLUTION

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For additional information, please see the following article in the Microsoft Knowledge Base:

Q191014 XGEN: How to Obtain the Latest Exchange Server 5.5 Service Pack

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 3.

Additional query words: word-wrap truncated deleted

Keywords : exc55 EXC55SP3Fix
Version : winnt:5.5
Platform : winnt
Issue type : kbbug