After you move mailboxes that contain Information Rights Management (IRM) protected email messages to a Microsoft Exchange Server 2010 Service Pack 1 (SP1) mailbox server, the Microsoft Exchange Mailbox Assistants service (MSExchangeMailboxAssistants.exe) crashes frequently. Additionally, the following event is logged in the Application log:
Log Name: Application Source: MSExchange Common Date: Date Event ID: 4999 Task Category: General Level: Error Keywords: Classic User: N/A Computer: Computer Description: Watson report about to be sent for process id: Process ID, with parameters: E12, Build Type, Version Number, MSExchangeMailboxAssistants, M.E.Data.Storage, M.E.D.S.RightsManagedMessageItem.EnsureIsDecoded, System.InvalidOperationException, XXXX, Version Number. ErrorReportingEnabled: False
This issue occurs because the conversation assistant cannot handle IRM-protected messages that are not decoded when it tries to create conversation view after the mailbox is moved.
To resolve this issue, install the following update rollup:
2645995 Description of Update Rollup 1 for Exchange Server 2010 Service Pack 2
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about Information Rights Management (IRM), visit the following Microsoft website: