MAPI Operation Failures

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool has determined that the server has many reported MAPI failures. Some MAPI operations are expected to return errors occasionally. However, sometimes a client application may not respond to the error correctly. As a result, the application may reissue the RPC request that caused the error, thereby increasing the load on the server.

An example of a frequent client error is when a MAPI client requests a list of items in batches and continues to request the items after the request has been returned by Exchange. For example, a client computer may request all items in a given folder that contain an attachment. The client may further request that the items are returned in batches of 30 items each. In some cases, after the Exchange server has returned the last item in the request, the client will continue to request a new batch of 30 items. In these cases, Exchange returns a "Not Found" error. If the client computer continues to request items even after the "Not Found" error is returned, the client computer is not responding to the error correctly. In this scenario, Exchange Server User Monitor (ExMon) would report multiple MAPI failures. In this case, although the ratio of failures to number of operations is high, the high failure rate is expected. MAPI operations with expected high failure rates include, GetPerUserGuid, ImportMsgMove, and Logon.

To correct this error

  1. Use ExMon to determine which user or group of users is causing the high number of MAPI failures.

  2. Determine what application on the client computer is causing this problem.

  3. Fix or remove the application that is causing the problem.

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