You notice high CPU usage when the IMAP service is running on an Exchange 2007 Service Pack 1 server that has the CAS role

On a Microsoft Exchange Server 2007 Service Pack 1 (SP1) server that has the Client Access server (CAS) role, you may notice high CPU usage when the IMAP4 service is running. As a result, the client computer may not be able access the server, or it may get a slow response from the server.

This issue occurs because the Microsoft.Exchange.Imap4.exe process falls into an inefficient loop when Exchange Server 2007 processes some search operations.

To resolve this problem, install Update Rollup 7 for Exchange 2007 Service Pack 1.

For more information about Update Rollup 7 for Exchange Server 2007 Service Pack 1, see the following Exchange Help topic: For more information about how to obtain the latest Exchange service pack or update rollup, see the following Exchange Help topic:Note This hotfix also improves the performance of the IMAP SEARCH command.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.