Post-office Box

A post-office box or Post Office box (commonly referred to as a PO box or a Postal Box) is a uniquely addressable lockable box located on the premises of a post office station.

In many countries, particularly in Africa, and the Middle East there is no 'door to door' delivery of mail. For example, should one post mail to a street address in Namibia, it will be returned to sender as undeliverable. Consequently renting a PO box has traditionally been the only way to receive mail in such countries, although some, like Jordan, are now introducing home delivery.

Generally, post office boxes are rented from the post office either by individuals or by businesses on a basis ranging from monthly to annual, and the cost of rent varies depending on the box size. Central business district (CBD) PO boxes are usually more expensive than a rural PO box.

In the US, the rental rate used to be uniform across the country. Now, however, a postal facility can be in any of seven fee groups by location; in addition, certain customers qualify for free box rental.

In the United Kingdom, Royal Mail PO boxes are often little more than pigeon-holes in the secure section of a Sorting Office, and are only accessible by staff. In such cases, the renter of the PO box will be issued with a card showing the PO box number and delivery office name, and must produce this to the desk staff when collecting mail. For an additional fee, the Royal Mail will deliver received items to the renter's geographical address.

Some private companies, e.g. United Parcel Service(UPS), also offer similar services of renting a mailbox in a public location. The difference with an official PO box is that mail sent there is addressed to a street address (along with the box number), instead of just addressed to "PO Box xxx".