In the latter part of the 19th and early part of the 20th century, a number of countries maintained post offices in foreign countries, arranged by treaty. Small-town post office and town hall in Lockhart, Alabama A post office is a facility (in most countries, a government one) where the public can purchase postage stamps for mailing correspondence or merchandise, and also drop off or pick up packages or other special-delivery items. ...
Most such offices were operated by European powers in the Middle and Far East. They were partly motivated by the desire to provide reliable postal service for merchants and other foreign nationals in major cities, and partly by suspicion of the local postal service.
The currency in use could be either the local currency, or that of the home country.
Philatelically, foreign offices are an interesting and sometimes complicated area of study.
The postoffice will forward (send) to your new address all mail addressed to your old address and will continue this service for 12 months after the date the change of address card is filed.
To apply for a postoffice box (usually called a "P.O. Box"), go to the nearest regular postoffice; bring with you some piece of identification that has your address on it, such as a state driver's license.
Postoffice lobbies (where boxes are located) usually are open 24 hours a day, every day of the week; however, some lobbies are closed on Sundays.