Wiktionary
n. A box in which post can be left by a sender to be picked up by a courier or postman (postal worker).
Wikipedia
A post box ( British English and others, also written postbox; known in the United States and Canada as collection box, mailbox, letter box, or drop box) is a physical box into which members of the public can deposit outgoing mail intended for collection by the agents of a country's postal service. The term post box can also refer to a private letter box for incoming mail.
Usage examples of "post box".
Please reply to the usual post box and destroy this as five have agreed.
I addressed the envelope to Master Tricki Pumphrey, Barlby Grange and slipped it into the post box with only a slight feeling of guilt.
The next afternoon, Sunday, he mailed a plain brown envelope, well sealed and with an excess of stamps, from a post box in the Elephant and Castle.
If Kowalski had letters to post, he waited by the post box inside the main hall of the building until five minutes before collection time, dropped the mail through the slit, then waited until the entire boxful was collected and taken back into the heart of the building for sorting.
At five to noon on the eighteenth, he entered the post office, was directed to the post box, and dropped the bulky package in.
Please reply to the usual post box and destroy this as we have agreed.
Omally strode off in the direction of the post box, leaving the master of the iron fist on the dusty ground thrashing his arms and legs and cursing between tightly clenched teeth.
ROBERT PROUST retrieved the letters from his private post box at the Capucines Station and rushed back to the privacy of his apartment.