Microsoft KB Archive/278444

= XCON: MTA Queue Building Up with No Association Opening =

Article ID: 278444

Article Last Modified on 10/26/2006

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APPLIES TO


 * Microsoft Exchange Server 5.5 Standard Edition

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This article was previously published under Q278444





SYMPTOMS
Messages may loop in a site when high-priority messages are sent. Message loops result in non-delivery reports (NDRs).



CAUSE
This problem can occur because of the way that high-priority messages are handled. The sequence of events is as follows:
 * High-priority messages are submitted on a server with a local X.400 connector to the destination site. A new association is opened for each message; as a result, nine associations are opened between the two sites.
 * When the next message arrives, the server tries again to open a new association. The attempt does not work; it is rejected by the remote end because the limit has been reached (the remote server logs a 57 event). If there are other servers in the site that have equal-cost X.400 connectors to the remote site, the message transfer agent (MTA) relays new high-priority messages to a second bridgehead server. A similar process occurs; up to nine associations are made between this second server and the remote site.
 * After all these associations are used, messages are relayed to a third server.
 * After all the associations have been used on the third server, messages are relayed back to the first. The first server now generates an NDR for the message with a loop detect. The loop is detected by using the internal trace information for each message extension.
 * After all the associations are open, even normal priority messages start to loop.



RESOLUTION
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Microsoft Exchange Server version 5.5 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this fix should have the following file attributes or later:

Component: MTA



STATUS
Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5.

Additional query words: looping fails

Keywords: kbhotfixserver kbqfe kbbug kbexchange550presp5fix kbfix kbqfe KB278444

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