Michael, as you and Topsie and probably somebody else(s) mentioned, the address is a P.O. box. These are difficult, perhaps even impossible, to live in. No running water or electricity, for one thing. State College is a real place it seems, even if Joe can't find it with a map.

While Max obviously has a mailbox there, I suspect he lives in a castle tower that only exists in this space-time continuum some of the time. I can't prove it, though.