After upgrading to Exchange 2010 SP1 you may see the following warnings logged on CAS:
Log Name: Application
Source: MSExchange ADAccess
Date: 8-8-2010 08:35:30
Event ID: 2937
Task Category: Validation
Process w3wp.exe () (PID=2024). Object [CN=Mark E. Smith (Lab),OU=Test Users,DC=CapaxGlobal,DC=lab]. Property [HomeMTA] is set to value [capaxglobal.lab/Configuration/Deleted Objects/Microsoft MTADEL:65235e09f-f18a-4c85-bf5d-bca5a226628c], it is pointing to the Deleted Objects container in Active Directory. This property should be fixed as soon as possible.
This is a benign warning that should only happen once per mailbox IF the HomeMTA of the mailbox no longer exists in the Exchange Org. You can correct it by calling update-recipient: