LBX meaning in Computing ?

What is Letterbox mean?

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

A slot in a wall or door through which mail is delivered (through-door delivery)A box attached directly to the building (direct-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 also known as a "flock" throughout the South Island of New Zealand and parts of America.A centralised mail delivery station consisting of individual mailboxes for multiple recipients at multiple addresses in a particular neighborhood or community reference