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Admin sessions are exhausted as a result of delegate access in an Exchange Server 2010 environment

Consider the following scenario:
  • You install Microsoft Exchange Server 2010.
  • You delegate some management roles.
  • The delegates have Full Access permissions to some mailboxes.
  • The delegates perform actions on the mailboxes at the same time.
  • The actions generate copy-on-write delegate access requests and create many admin sessions. For example, more than 10,000 admin sessions are created.
  • You try to run an Exchange Server cmdlet. For example, you try to run the Test-MapiConnectivity cmdlet to verify server functionality in a mailbox.
In this scenario, the cmdlet may fail. For example, one or more of the following events are logged in the Application log when you try to run the Test-MapiConnectivity cmdlet:

Time: Time
ID: 14035
Level: Error
Source: MSExchange MailTips
Machine: Computer
Message: Process Microsoft.Exchange.InfoWorker.Common.Delayed`1[System.String]: MailTips query failed for mailbox Mailbox. Latency: total:7. The returned exception is: Microsoft.Exchange.Data.Storage.TooManyObjectsOpenedException: Cannot open mailbox /o=Organization/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=Computer/cn=Microsoft System Attendant. ---> Microsoft.Mapi.MapiExceptionSessionLimit: MapiExceptionSessionLimit: Unable to open message store. (hr=0x80040112, ec=1246)

Time: Time
ID: 1006
Level: Warning
Source: MSExchange Mailbox Replication
Machine: Computer
Message: The Microsoft Exchange Mailbox Replication service was unable to process jobs in a mailbox database.
Database: Database
Error: MapiExceptionSessionLimit: Unable to make connection to the server. (hr=0x80040112, ec=1246)

This problem occurs because the maximum number of admin sessions on the Exchange Server 2010 mailbox server is 10,000. Therefore, no more admin session can be created when 10,000 copy-on-write delegate access requests to the mailboxes are issued.
To resolve this issue, download and install Update Rollup 4 for Exchange Server 2010 Service Pack 2. For information about how to download and install Update Rollup 4 for Exchange Server 2010 Service Pack 2, visit the following Microsoft website:

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 the Test-MapiConnectivity cmdlet, go to the following Microsoft website:
For more information about Update Rollup 4 for Exchange Server 2010 Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:

2706690 Description of Update Rollup 4 for Exchange Server 2010 Service Pack 2


Article ID: 2726897 - Last Review: 09/04/2013 09:16:00 - Revision: 4.0

Microsoft Exchange Server 2010 Standard, Microsoft Exchange Server 2010 Enterprise

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