XCLN: Exchange Server Performance Problems Caused by Clients That Open Large Numbers of Messages

General Exchange Server performance and stability problems may be caused if a client application opens a large numbers of messages at once. Some add-on services and applications may inadvertently do this while performing their functions.

Symptoms may be non-specific and can include slow performance on the server or unexpected program exits by clients. You may also observe Out-of-Memory errors on the Exchange Server computer. Examination of Exchange Server-related errors in the server Application log may show errors with the following IDs in the event descriptions:

• 0x800700E
• 1014
• CdoE_NOT_ENOUGH_MEMORY

For Exchange Server 5.5 and earlier, you must address the problem from the client. Exchange 2000 provides two server-side options for dealing with this problem:

• Limit the number of open messages for each client logon.For additional information, click the article number below to view the article in the Microsoft Knowledge Base:
  289109 XADM: Limit the Number of Messages Opened per MAPI Logon
• If you find that a particular client version is problematic in your environment, you may prevent all clients of this version from connecting at all to the Exchange 2000 server.

Microsoft has confirmed that this is a problem in Microsoft Exchange 2000 Server.
Microsoft has confirmed that this is a problem in Microsoft Exchange 5.5 Server.

You can view the number of open messages for each client logon in the Exchange Server 5.5 Administrator program or in Exchange System Manager for Exchange 2000. A client logon is suspect if it shows more than 1,000 messages open for more than a few minutes at a time.

To check the open message count:

1. Start the Administrator program for Microsoft Exchange Server 5.5, or Exchange System Manager for Exchange 2000.
2. Expand the mailbox database object, and then click Logons.
   
   NOTE: In Exchange Server 5.5, this database is always the private information store. In Exchange 2000, the database name is set by the administrator.
3. On the View menu, click Columns, and then add "Open Messages" to the displayed columns.

Note that the column display does not refresh automatically, and values in it are updated at approximately one minute intervals.