This TechNet Wiki page explains how you move the arbitration mailboxes from the default mailbox database to another mailbox database in Exchange 2010.

 

 


When you try to delete the Default Mailbox Database (created with 1st installation of the Mailbox Role), you receive the error below:

“This mailbox database contains one or more mailboxes or arbitration mailboxes. Before you can remove this mailbox database, you must disable, move or remove user mailboxes and move arbitration mailboxes.”

Why?

The First database contains the SystemMailboxes which are the Arbitration mailbox(es).

We have to move these system mailboxes to another database before of remove the Default Database.

1. Find the Arbitration Mailbox using the Exchange Management Shell (EMS):

Get-Mailbox -Arbitration | Where {$_.Name -like "SystemMailbox*" } | ft –wrap

2. Now create a new move request in order to move the system mailboxes to another mailbox database:

New-MoveRequest -Identity "SystemMailbox{1f05a927-32d1-4e19-8ea5-67eba859f541-yourGUID}" -TargetDatabase "dbxxxx"

3. Verify whether the move request completed:

Get-MoveRequest

4. Now remove the move request

Remove-MoveRequest -Identity "the name of the request like Microsoft Exchange Approval Assistant"



For more Detailed Steps
How to remove default database in Exchange 2010 in a recommended way