How to find and move the Exchange Arbitration Mailboxes

The Exchange System (Arbitration) Mailboxes, like ‘Discovery Search’ are created on the first Exchange server installed in the organization. If you need to remove a database or uninstall Exchange you will need to move the arbitration mailboxes to a different database or different server, respectively.

Command to search all databases for the arbitration mailboxes:
get-mailboxdatabase | Get-Mailbox -Arbitration |ft name,database,servername

Here is the command to determine if arbitration mailboxes are contained in a specific database:
Get-Mailbox –Database “Mailbox Database 1” –arbitration

Note: if your Exchange server is in a child domain it will appear that the arbitration mailboxes are missing. Use this command so that your get-mailbox commands will search all domains:
Set-ADServerSettings -ViewEntireForest:$true

Command to move all the arbitration mailboxes in the specified database to a new target database:

Get-Mailbox –Database “Mailbox Database 1” –arbitration | New-MoveRequest –TargetDatabase “Mailbox Database 2”

Check the status of the move and verify it has completed:

Note: If you are trying to uninstall one of your Exchange servers or remove a database and you haven’t moved the Arbitration mailboxes you may receive an error similar to the following: “This mailbox database contains one or more mailboxes, mailbox plans, archive mailboxes, or arbitration mailboxes.”