XCON: Duplicate Messages Delivered After MTA Restart

• Microsoft Exchange Server, version 5.5 SP2

SYMPTOMS

When the message transfer agent (MTA) is under heavy stress, Db*.dat files are sometimes not cleaned up properly. In some cases, these files are also not marked as "used." When the MTA is restarted, the queues are rebuilt based on all of the Db*.dat files that are "not used" in the Mtadata folder. Because these files have not been cleaned up or marked as delivered, restarting the MTA in this state produces duplicate mail to the local store.

In addition, when the MTA is in this state it cannot be shut down cleanly. Consequently, either killing the MTA or hard-booting the server are the only options to bring it down.

CAUSE

Viewing the Performance Monitor counter MSExchangeMTA, with the instance Work Queue Length, reveals a steady increase but no message backlog in any other queue. This is a result of the Db*.dat files not being marked as "used."

RESOLUTION

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Microsoft Exchange Server version 5.5 service pack that contains this fix.

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 on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5.

Additional query words:

Keywords : exc55sp2
Version : winnt:5.5 SP2
Platform : winnt
Issue type : kbbug