Yes. It is possible to move mailboxes between storage groups or databases on the same server without making any changes inside of ERM. However, in the event that the mailbox will move between servers additional steps are necessary to complete the move:
- Make sure both servers are running Exchange Resource Manager
- Note any per-resource configuration changes for the resource
- Un-Manage the mailbox while it resides on the source server
- Move the mailbox to the destination server
- Re-Manage the mailbox on the destination server
- Re-create any per-resource configuration changes