In any Exchange organization, it is common to add and remove mailbox databases, especially the default ones Exchange creates with the install.

Generally when you want to remove a mailbox database you would need to move any mailboxes, arbitration mailboxes, archive mailboxes, plans, etc. however in Exchange 2016 there is one more.

If you try and remove a mailbox database or perform an uninstallation of Exchange 2016 you are presented with the following error:

The reason is that in Exchange 2016 you now have an Audit Mailbox, you can check this by running the following command:

  • Get-Mailbox -Auditlog

As you can see in the last command we have a system mailbox, you can now move it to another server as shown below:

You can run the new-move request command to move it to another store and then you can proceed with your cleanup or removal of Exchange 2016.