Sign in with Microsoft
Sign in or create an account.
Select a different account.
You have multiple accounts
Choose the account you want to sign in with.


This update is no longer available. To fix the issues that are described in this article, install the latest Microsoft Exchange Server update from the following Microsoft Learn article:

Exchange Server build numbers and release dates

Microsoft provides download files only for N-2 versions for an Exchange Server cumulative update (CU), where "N" is the latest CU. The latest CU can be used to recover servers that are running Exchange Server. This includes servers that have a previous CU installed.


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:


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.


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:

General information about the Test-MapiConnectivity cmdlet


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


Need more help?

Want more options?

Explore subscription benefits, browse training courses, learn how to secure your device, and more.

Communities help you ask and answer questions, give feedback, and hear from experts with rich knowledge.

Was this information helpful?

What affected your experience?
By pressing submit, your feedback will be used to improve Microsoft products and services. Your IT admin will be able to collect this data. Privacy Statement.

Thank you for your feedback!