We had the following alert appear on our Exchange Server recently.
“Process powershell.exe (PID=19640). Object [CN=Username,OU=Mailboxes,OU=OU,DC=Domain,DC=com]. Property [HomeMTA] is set to value [Domain.com/Configuration/Deleted Objects/Microsoft MTA
DEL:d016338e-12ce-409b-a82a-da6217c8e67f], it is pointing to the Deleted Objects container in Active Directory. This property should be fixed as soon as possible.”
Basically the issue is that the user referenced in event has an incorrect homeMTA value. If you browse to the user via ADSI edit and view the attribute homeMTA you will see that it references deleted objects.
To sort this issue run the following command
get-mailbox –identity USERNAME | Update-Recipient