Some more reading on it. It says someting about re-created mailboxes in there which does not sound very positive. You should probably search this on the MSFR site too.
How Recovery Storage Groups Work
Before you begin using Recovery Storage Groups, you should have a general understanding of how they work, and what their limitations are.
The most important limitation on the use of a Recovery Storage Group is that the Active Directory topology of the Exchange system must be fully intact and in the same state as when the copy of the database was made. In practical terms, this means that the mailboxes you are trying to recover should not have been deleted and purged from the system, or moved to other databases or servers.
The RSG is usually not an appropriate tool when entire servers have been destroyed, or you are in an emergency situation that requires changing or rebuilding your Active Directory topology. The RSG is intended as a substitute for situations where previously you would have built an alternate forest recovery server, specifically:
•You want to recover deleted items for a mailbox that the user mistakenly purged.
•You want to recover or repair an alternate copy of a database while another copy remains in production (and, typically, with the final intent of merging data between the two databases with the EXMerge utility).
For security and data extraction reasons, original databases and mailboxes and the copies in the RSG are logically linked. Only databases that still exist in the Exchange organization can be added to a Recovery Storage Group. Further, mailboxes that are candidates for data salvage in an RSG must still exist in the original database location, and must not have been deleted and re-created.
When you delete a mailbox, unique identifying information is destroyed. A new mailbox with the same name or linked to the same Active Directory user account is not really the same mailbox as before. This is similar to what happens when you delete and re-create an Active Directory user account. Even if the new account has the same name, it is fundamentally a different account, and none of the security associated with the previous account will be inherited by the new account.
If you have purged a mailbox from its original database, you cannot use a Recovery Storage Group to salvage data from the mailbox. However, you can mount a copy of the database in an ordinary storage group to recover a purged mailbox. See the section How the RSG Links Back to the Original Database for more information about this.
To reiterate, Recovery Storage Groups are not designed for recovery from a general disaster involving multiple servers or storage groups. They are intended for recovery scenarios where:
•The logical information in Active Directory about the storage group and its mailboxes remains intact and unchanged, and
•Data recovery is required for a single mailbox, a single database or a group of databases in a single storage group.
