Handle the cases where a user tries to subscribe an already subscribed mailbox or unsubscribe one that isn't subscribed.
Handle the cases where a user tries to subscribe an already subscribed mailbox or unsubscribe one that isn't subscribed.

darcs-hash:20070512143002-1210e-7cd96ee426aa821f841147940840d4f29eae8ca4

JonathanGuthrie/wodin