Here's the USPS Zip Code lookup page: LINK.

I mail out over 1000 periodicals per week and we have to have Zip+4 to get the lowest rate. If your address doesn't come up exactly, it's not correct. I can tell you horror stories about screwy street names, streets that the city/county calls one thing, google maps calls another, and the USPS calls something different than the other 2. I have the PO Box/Street Address issue at work, and now get most of my shipments at home (plus my office is closed Friday and Saturday).

FedEx is totally random about where they throw a package. The UPS driver at the office is a local small-town guy, still lives in town, knows everybody, and has enough seniority to keep the route to himself. If he sees me out in town before he gets to me, he'll flag me down and give me my stuff. I've been eating lunch when he comes in and gives me something because he saw my car in the parking lot. He knows if the office is locked, he can take the stuff across the street to the woman that does daycare and leave it with her. He said he gets GREAT tips at Christmas.