Mailboxes for the user's deleted from the active directory do not show up in the restore selections when the data is backed up to a tape.
Details: This behavior is by design.
Explanation : When Running the GRT backup to tape , the exchange data is backed up in the native format ,along with the ese.dll and other supporting files,Later the MAPI is initialize on the exchange server by RAWS (Remote agent for Windows Server) to gather granular restore information .MAPI gathers the exchange data using Active directory and then writes to the catalog. As MAPI cannot retrieve the information about the deleted user from the Active directory the catalog information for the user is not written to the catalog. this is not a problem with restore selection from backup to disk folder due to the Dynamic way we can read the exchange DB using the VFF technology
Workaround : Duplicate the backup set from tape to disk