Mailbox Move Error Duplicated Mailbox Was Found

You might have face this error message when doing Exchange 2007 to Exchange 2010 transition.

” A duplicated mailbox was found due to problem during a Move Mailbox procedure. The duplicate mailbox has been deleted.”


To check if there is a duplicate mailbox, please run the following Exchange cmdlet against the source and target mailbox database:

Clean-MailboxDatabase -Identity “<Exchange2010Server>\<StorageGroup>\<SourceorTargetMailboxDatabase>”

 After clean up the database on each mailbox databse, we need go to Exchange Management Console -> Recipient Configuration -> Disconnected Mailbox to check the duplicate mailbox.


Move the mailbox from Exchange 2010 console instead of Exchange 2007.  It should move the mailbox successfuly.