Topic Last Modified: 2007-01-23

The Microsoft® Exchange Server Analyzer Tool uses the Exchange Server User Monitor (ExMon) tool to determine whether user MAPI operations are taking longer than should reasonably be expected on a healthy server that is running Exchange Server.

As part of its analysis, the Exchange Server Analyzer reviews the ExMon data for user-issued MAPI Restrict operations that have taken longer than 30 seconds to be completed.

The MAPI Restrict operation is used by client applications to select items that match particular criteria. The server creates a view that is, effectively, a table with associated criteria called a restriction. If the view that has a matching restriction already exists, the server uses the existing view to satisfy the user request. When the server uses this view, this is a less expensive operation than when the server creates a new view. By default, the store caches only 11 views for each folder. If the server is asked to create a twelfth view, it deletes the oldest cached view and creates a new view. Views add overhead to all actions on items.

If the Exchange Server Analyzer determines that a user-issued MAPI Restrict operation has taken longer than 30 seconds, the Exchange Server Analyzer displays an error.

MAPI Restrict operations that take longer than 30 seconds may not always be a problem. However, if the user or users experience frequent delays or delays that adversely affect their messaging experience, these delays may indicate that a user application is causing new views to be created.

To address this error, work with the user who is experiencing the high latency to determine the following:

To address this issue, follow these steps:

Some applications can significantly increase server load without issuing lots of MAPI operations. This is because some operations are more expensive than other operations. It may take only a small increase in the number of costly operations to noticeably affect server performance. In ExMon, users are reported as having a high CPU effect, without necessarily having issued many MAPI operations.

Also, you should be aware that when there is a bottleneck for resources, generally a disk or CPU bottleneck, the latencies for the Restrict operations will increase.

For More Information

For more information about the MAPI Restrict operation, see the Microsoft Exchange Team Blog, "Putting the Restrictions on Restrictions" (

The content of each blog and its URL are subject to change without notice.

For more information, see the following Exchange Server resources: