To recover a deleted mailbox, the mailbox must be in either a mounted online database or a recovery storage group. With Exchange you have two options available to recover deleted mailboxes:

• Recovering content from a deleted mailbox while the message is still in the dumpster   Good retention practices can help you avoid having to restore an Exchange 2007 database to recover a deleted mailbox. When a mailbox is deleted, it goes into a dumpster on your Exchange Server by using an Exchange feature called mailbox retention. This dumpster will hold the mailbox for a configurable number of days (30 days by default) or until a full backup of your Exchange database is run, whichever comes first. You can recover the deleted mailbox by using either the Exchange Management Shell or the Exchange Management Console. For information about recovering a deleted mailbox that is still in the dumpster, see How to Recover a Deleted Mailbox.
  
  
• Recovering mailbox content from a backup   After a mailbox has been removed from the dumpster, the only way to recover the mailbox is with a restore of the database that the mailbox was in from a point in time when the mailbox was still in the database. For information about recovering a deleted mailbox that is no longer in the dumpster, see How to Recover a Mailbox by Using a Recovery Storage Group.
  
  

  Note:
  There are third-party backup applications that allow you to back up and restore at the mailbox level.

For information about configuring deleted mailbox retention, see How to Configure Deleted Mailbox Retention and Configuring Deleted Mailbox and Deleted Item Retention.

For information about recovery storage groups, see Recovery Storage Groups.