My mailing address is different then my street address. The application as I recall required both address. My FFL clearly has the premise address and the mailing address. Shippers can ship via common carrier to the premise address and via USPS to the mailing address. I usually ask sellers to "combine" the two address so that they don't fear something is funny. Since my PO box is a number and the name of my development, it helps get it here via common carrier. Usually I tell the seller to do this:
My Name
2345 Development name
345 My Street St.
Town, ST zip
Many 01 FFL's have a similar situation in rural areas. I've gotten several licenses from 01 FFL's that were just like mine with different premise and mailing addreses. I believe most people that ship guns regularly know which address to use for the method of shipping they use. If someone really gave me a hard time, i'd just ask them to call ATF. You're not asking anyone to do anything illegal. Both addresses are on your license and both are necessary for you to get packages depending on the shipper!!
later,
AJ