Recovering Deleted Items or Purged Mailboxes Using a Recovery Storage Group in Exchange Server 2003
Microsoft® Exchange mailboxes can exist in one of three states:
Connected The mailbox is linked to a Microsoft Active Directory® directory service user account—specifically, there is an Active Directory user account whose msExchMailboxGUID attribute specifies the mailbox GUID and whose homeMDB attribute specifies the distinguished name of the mailbox database. (There are also several other mailbox-related attributes that are set on the user account that owns a mailbox.)
Disconnected The mailbox GUID is not set on any Active Directory user. When an Exchange administrator deletes a mailbox, the mailbox itself is not affected, but the Active Directory user object associated with the mailbox is stripped of all its mailbox-enabling attributes.
Purged The mailbox contents no longer exist in the database. By default, this occurs 30 days after an administrator deletes a mailbox. Until a mailbox has been purged, it can be reconnected to the previous Active Directory user account or to a different Active Directory user account.
If a mailbox is not connected to an Active Directory user account, ExMerge cannot log on to the mailbox and extract data from it. Although mailboxes in the recovery storage group are disconnected, they are logically linked to mailboxes in the original database by the msExchOrigMDB attribute and the mailbox GUIDs. If a connected mailbox with the same GUID exists in that original database, the Exchange Server 2003 version of ExMerge can use that connection to access the appropriate mailbox and merge the recovered content into the original mailbox.
In Exchange System Manager, mailboxes in a recovery storage group may appear in the connected state under some circumstances, such as when you restore a database from an offline file copy. The mailboxes are not actually connected, but you cannot change the appearance of the mailboxes with Run Cleanup Agent because this function is also disabled in a recovery storage group. Regardless of the mailboxes' appearance, they are actually disconnected.
Ordinarily, recovering a deleted Exchange mailbox is a straightforward operation. If the mailbox still exists in the original database, you can right-click it in Exchange System Manager and connect it to any Active Directory account that you want. This has the effect of "undeleting" the mailbox. You can then access items as if the mailbox had never been deleted.
However, if you have purged a mailbox (or items from it) that must be recovered, you must then restore a backup of the database that still contains both the mailbox and the items. If the mailbox is still in its original connected state, a recovery storage group can be used to extract purged items. However, a recovery storage group cannot be used to extract data if the entire mailbox has been purged or moved.
Nonetheless, the recovery storage group can be useful in recovering a purged mailbox. As described earlier, when using a recovery storage group, data restore and data extraction are two separate recovery steps. You can restore a database containing a purged mailbox to a recovery storage group and then move the database to an ordinary storage group to perform data extraction for a purged mailbox. In Exchange 2000 Server, it is necessary to restore the database to a separate recovery server. Using a recovery storage group saves you the trouble of building such a server. (This capability also permits testing of backups without having to restore to a separate server.)
Exchange allows you to run a maximum of 20 databases in four storage groups on a single server, with up to five databases in any one storage group. Because recovering a purged mailbox requires that you move a restored database to an ordinary storage group, the server involved can contain no more than 19 databases currently running on it. If you have an entire unused storage group, that is even better, because it further isolates the recovery process from other databases and reduces the chance of a mistake. For detailed instructions about how to recover a purged mailbox, see How to Recover a Purged Mailbox from an Online Backup Using the Original Database Server.