Most dormitories, campus buildings, and large apartment buildings also have places for outgoing mail. If you have your own mailbox, ask a neighbor or your postal carrier what you need to do to have your outgoing mail picked up. Check with the post office for current overseas air mail rates. A post office clerk can explain the various rates for mailing packages within the United States or overseas. You can send packages or letters overnight or within two days to certain places in the United States or overseas using express mail or air courier services.
Express mail costs more than regular delivery.
When you give someone your mailing address, make sure you include your zip code. Or, you may look the zip code up in your post office's zip code directory. I will probably move around a lot while I'm in the United States. When you give someone your permanent address, use the box number, city, state, and zip code.