"The street finds its own uses for things."

Where I am (Australia) theres a whole bunch of places that'll provide "non Post Office PO boxes" who're perfectly happy for you to address things to "Suite 306" or "Apartment 306" as well as "PO Box 306" at whatever address the box is located. Fools _most_ of the "must be a real address, not a PO Box" restrictions.

(Interestingly StartSSL failed me on that once when I gave one of those as a personal address - they mailed me saying "that looks like a business address, we need a personal home address for personal identity validation") - I dunno of they Google Street-viewed it or of they've got some automated system that flagged it...)