This article was previously published under Q254812
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Message transfer agent (MTA) queues to the private or public information stores may increase during the day. The MTA does not stop delivering e-mail, but it is sluggish and only delivers approximately three to five messages each minute.
This may happen randomly on servers throughout the organization. Performance improves when fewer users work on the server, usually later in the afternoon. The MTA queue clears within an hour of the close of business. The following day the affected server behaves normally. When the MTA queues are large, users may experience a delay in e-mail delivery (incoming e-mail messages), but outgoing e-mail messages are not affected.
This issue can occur because of a space tree issue. Exchange Server tries to coalesce a page that is being freed with one of the neighbors of the page and navigates thousands of empty btree pages when it does so.
To resolve this problem, obtain the latest service pack for Exchange Server 5.5. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
191014 XGEN: How to Obtain the latest Exchange Server 5.5 Service Pack
To work around this issue:
Restart the server.
Perform an offline defragmentation.
Add more random access memory (RAM).
Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 4.
This issue is a variation of a space tree issue. For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
230691 XADM: Space Tree Fragmentation in Exchange Database Engine Can Degrade Server Performance
234702 XGEN: MTA Queue to Information Store Processing Slowly