That's usually who we contact! All we have to do is show them our paperwork and they are more than willin' to help us out! Have yet to be turned down!
A lot has to do with the post master. Most, if not all, will cooperate.
When I worked for a delivery company, I went to a small post office to ask directions for a package with a PO Box for an address. The post master told me that according to postal regs, he couldn't tell me where the house was, but he walked outside with me, pointed and said: "You see that blue house on the hill. That's it."
