By default you are unable to restore data from a expired tape. Also the recatalog option is disabled for expired tapesWhen a has expired in DPM 2007. But you can use the following work around.
Note: On the restore tab you will find the items under External DPM Tapes
When you use this option to restore a Exchange mailbox; On the restore tab you will be unable to drive down to mailbox level. It is also not possible to restore to the Recovery Store Group (RSG).