Write the full name and address of the recipient of your letter in the center of the envelope. Print clearly in large letters. Include the name of the country it's going to for overseas mail. Fill out your return address in the upper left-hand corner and include "USA." Use a regular standard white envelope or purchase special airmail envelopes and stationery from an office supply or stationery store.
Ask the postal clerk for an airmail etiquette label indicating that the letter is to go by airmail. Affix the little blue sticker that has "Air Mail" printed on it at the bottom or off to the side of the envelope. Write the words "Air Mail" or "Por Avion" directly on the envelope if you don't use the sticker. This is not usually required but gets the attention of the clerk. Get the etiquette labels from airlines or hotels, if possible, as they're often decoratively printed.
Weigh the letter with scales, then check the U.S. Postal Service website to determine the postage for the letter (see Resource), or ask the clerk at the post office to do it for you. Ask the clerk for airmail stamps; the post office may have some older ones available. Use regular stamps for the amount of postage if the post office doesn't have airmail stamps. Don't fill out a customs form, as it's not required for airmail letters.
Package a box for overseas airmail shipment securely, sealing all edges with tape. Address it, including the return address. Weigh and measure the box, then check the U.S. Postal Service website to select the type of service you will use to mail it, based on expense and speed of delivery. First Class is the cheapest, while Priority International is faster. Express Mail is very fast but expensive.
Take the package to the post office, where the clerk will affix the proper postage label to the box. Ask the clerk for a customs form and fill it out completely, describing the contents and value of the package.
