Consider the following scenario:
You use service accounts to access mailboxes that are hosted on Microsoft Exchange Server 2010.
The service account tries to access an Exchange Server 2010 mailbox.
Transient communication errors occur in Active Directory Domain Services (AD DS).
In this scenario, communication with Active Directory may fail. When this issue occurs, the connection may be throttled at default levels instead of at the levels for a service account. Therefore, fallback information may be deposited in the throttling policy for the service account. When this issue occurs, services or applications that rely on the service account do not receive information from the Exchange server.
For example, when this issue occurs, BlackBerry users cannot synchronize their mailboxes with the Exchange server.
Additionally, Event ID 2915 is logged in the Application log on the Exchange server. The following is a sample of the event that is logged when this issue occurs:
Source: MSExchange ADAccess
Message: Process Microsoft.Exchange.RpcClientAccess.Service.exe (PID=5372). User 'Sid~DOMAIN\SERVICEACCOUNT~RCA~false' has gone over budget '263' times for component 'RCA' within a one minute period. Info: 'Policy:[Fallback], Parts:MaxConcurrency:262;'. Threshold value: '100'.
To resolve this issue, install the following update rollup:
2685289 Description of Update Rollup 3 for Exchange Server 2010 Service Pack 2
To work around this issue, restart the Exchange Server 2010 Client Access service.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.