Quite simple really. I have found that in certain situations, (help in backup) I have needed to delete databases (perhaps several databases exist on a single drive). You can move mailboxes from one database to another simply by typing the following cmdlet:
[PS] Get-Mailbox –Database TheDatabaseID | New-MoveRequest –TargetDatabase TheDatabaseID
Now this will move the ‘regular’ mailboxes but not those marked as arbitration mailboxes. You can identify those by using the following:
[PS] Get-Mailbox –Database TheDatabaseID –Arbitration
Now you know what mailboxes to look out for, move them to the database of preference.
[PS] Get-Mailbox –Database TheDatabaseID –Arbitration | New-MoveRequest –TargetDatabase TheDatabaseID.
And then check that the arbitration mailboxes have been moved to an alternative database. You can also check out the move requests themselves:
Now that the mailboxes (hidden ones included) have been moved, try deleting the database now. It should work but remember that you will still have to remove the database files manually.
For Matt and Mark!