Event ID 9646 is logged on the Exchange Server 2010 mailbox server when you access a mailbox that has more than 250 folders by using an IMAP4 client

Symptoms

Consider the following scenario:
  • You have a mailbox that has more than 250 folders in a Microsoft Exchange Server 2010 environment.
  • You access the mailbox by using an Internet Message Access Protocol 4 (IMAP4) client.
  • The IMAP4 client issues a SELECT command or a STATUS command for each folder.
In this scenario, you cannot see all the message items in the mailbox. Additionally, the following event is logged in the Application log on the Exchange Server 2010 mailbox server:

Cause

Two objtMessageView objects are used when an IMAP4 client issues a SELECT command or a STATUS command for a folder. However, the Exchange server does not release one of the objtMessageView objects for the previous folder when the IMAP4 client issues another SELECT command or another STATUS command for a different folder. When the mailbox has more than 250 folders, the IMAP4 client exhausts the maximum number of the objtMessageView objects on the Exchange server, and this issue occurs.


Resolution

To resolve this issue, install the update rollup that is described in the following article in the Microsoft Knowledge Base: 
2685289 Description of Update Rollup 3 for Exchange Server 2010 Service Pack 2

Status

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

More Information

For more information about IMAP4 features and commands, go to the following Microsoft website:For more information about Exchange store limits, go to the following Microsoft website:
Properties

Article ID: 2699023 - Last Review: May 30, 2012 - Revision: 1

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