Can you use just zip code and coresponding (P.O. Box?) numbers (33312-xxxx) to mail something, or do you still need the physical address on the envelope?
Similar Question: What are the least amount of things needed on the envelope to mail it?
There is a boatload of information in the FAQ at http://www.usps.gov .
Give it a look and see if you can find what you want there.
If it’s a PO box, the answer is “Yes.”
Sorta.
A lot of PO boxes have Zip+4’s that don’t correspond directly to the box number. At the PO closest to me, for example, they have two ranges of box numbers: 9XXX and 90XXX. The Zip+4’s for the former are all 0XXX, where the XXX is the last three digits of the PO box, and the latter has Zip+4’s in the format of 1XXX, again with the last three digits being the same.
So, if you sent a letter to someone at a PO Box with only the Zip and Zip+4, it would get to them, provided you used the correct format.
When I was a kid (maybe 30-35 years ago) Mad Magazine published a picture of the envelope in which a letter had arrived. The Post Office delivered a letter to Mad Magazine addressed with only a picture of Alfred E. Neumann on the front. They were quite proud of this, it was presented as fact, not a joke.
FWIW, I’ve mailed letters using only street address and Zip code (no city/state) and the mail has gotten there fine, and on time. There’s no reason it shouldn’t, but it sure does feel strange writing an address without the city and state.