Below are the steps for an Exchange mailbox recovery. But before we give you the information you should be first aware this process which is time consuming could have been avoided in the first place with proper disaster recovery plan showing the way to recover mailboxes in your environment.

Private storage - Exchange mailbox recovery

The administrator can have a look into the private storage of the private storage where he or she will find all orphaned mailboxes with a red cross. The cleanup agent is the piece of software that regularly scans all mailboxes and checks, if there is a connection between a user object in Active Directory and a mailbox in the private information store. If there is not, it marks the mailbox for deletion. The retention time for the tomb stoned mailbox now begins to run. If the cleanup agent has not run yet, you can start him manually by triggering it.

Restoring an Exchange Mailbox using Exmerge.exe