The user directory attributes, such as homeMDB or msExchHomeServerName, may be missing or corrupted. Troubleshooting: Verify ...

{4}: The user directory attributes, such as homeMDB or msExchHomeServerName, may be missing or corrupted. Troubleshooting: Verify the integrity of the user directory attributes, and then run the Recipient Update Service again to make sure that the attributes that are required for transport are valid.