Exchange 2013 Hidden Mailboxes

In the graphical/web-based interface for Exchange 2013, the list of recipients does not include utility mailboxes such as:

• discovery search mailbox
• arbitration mailboxes

I recently had an issue at a client where rather than trying to fix an Exchange server having issues, we just replaced it and moved the mailboxes. However, before I could actually uninstall Exchange 2013 from the old server, I needed to move the mailboxes that did not appear in the graphical interface.

In the Exchange Management Shell (EMS), the discovery search mailbox is retrieved by the Get-Mailbox cmdlet. So, you can use the following to move the discovery search mailbox:

Get-Mailbox -Server RetiringServer | New-MoveRequest -TargetDatabase DBonNewServer

To get a list of the arbitration mailboxes, you need to use the -Arbitration switch with the Get-Mailbox cmdlet as shown in the screenshot below:

We had not implemented these, but other things that might trip you up are:

• archive mailboxes (use the -Archive switch)
• public folder mailboxes (use the -PublicFolder switch)

After you have removed all mailboxes from a database, then you can remove the database and finally, uninstall Exchange 2013. Uninstalling Exchange 2013 is the proper way to remove the server from the Exchange organization.

If you have not removed all mailboxes from a database before attempting to delete it, you will get the following error:

The mailbox database contains one or more mailboxes, mailbox plans, archive mailboxes, public folder mailboxes, or arbitration mailboxes.