The Windows Mobile Devices task logs an error similar to the following:
This can occur if the mailbox has been deleted but has not yet been purged from the Exchange Mailbox Database
Confirm the Mailbox exists and has the same SMTP Address as listed in the error. If the mailbox is no longer active, the error can be ignored and will no longer be logged once the mailbox retention period expires, the mailbox is purged from the Exchange Mailbox Database and a Default Gathering is successfully run.
