May i know whether if you have subsequent connected mailboxes for each and every disconnected mailbox which shows up under RSG?
- REsotre-mailbox will compare (Disconnected GUID) in RSG and (Connected Guid) in Production and will complete the operation and will fail if GUID's are not identical.
- when the guids are not identical then we must have to use Restore-Mailbox with -TargetFolder, -TargetMailbox switches
So, if we have mailboxes connected under production for every RSG mailbox then would need to redirect the restore to a folder for Eg: "Recovery" to production mailbox or few set of temporary mailboxes which you may create and can later use Export-Mailbox
with -IncludeFolders Switch Speficified as "Recovery".
With Exmerge on Exchange 2003 SP2 Exporting PST from the disconnected mailboxes used to be possible but not any more with the latest versions (E2K7 and later).
Other option you may try is already specified by "Jason Sherry" but in case if we have a connected mailbox for the user in production then you may not be able to connect the disconnected mailbox to another user as they may share the same LegacyExchangeDN.
in case if you want the PST's for the mailboxes which are disconnected in production and if you want to use RSG to recover data then we can get the PSTs using Export-Mailbox with a 32-bit Exchange 2007 management tools machine.
Once you have the mailboxes recovered to a normal database, using temp accounts\mailboxes,
you can then export the data to PST. See: How
to Export Mailbox Data
Working with RSG
http://technet.microsoft.com/en-us/library/bb266964(v=exchg.80).aspx
How to Recover a Mailbox by Using a Recovery Storage Group