A letter box, letterbox, letter plate, letter hole, deed, mail slot, or mailbox is a receptacle for receiving incoming mail at a private residence or business. For the opposite purpose of collating outgoing mail, a post box is generally used instead. Letterboxes or mailboxes consist of four primary designs:

• A slot in a wall or door through which mail is delivered (through-door delivery)
• A box attached directly to the house (door-to-door delivery)
• A box mounted at or near the street (curbside delivery)
• A centralised mail delivery station consisting of individual mailboxes for an entire building
• A centralised mail delivery station consisting of individual mailboxes for multiple recipients at multiple addresses in a particular neighborhood or community