【letter box】 —

1. (UK) a private box or other container to which mail is delivered:

• When I came back from holiday the first thing I found in my 【letter box】 was a letter refusing my proposal for the TV show.

2. (UK) a narrow opening in a door through which a mailman can push envelopes, cards, etc.:

• Mr. Marble, who was already awake … heard the newspaper pushed through the 【letter box】 of the front door downstairs.

3. a box in a public place in which letters are deposited for dispatch:

• Of all the clues, the most promising of all was that provided by the scrawl on a penny postcard, dropped in a 【letter box】 in Newark.

4. a film format for movies when shown on television:

• The term “ 【letter box】 ” was originally coined by 20th Century–Fox when CinemaScope first appeared in 1953.

【mailbox】 —

1. (U.S.) a private box to which mail is delivered (in some areas the resident signals the mailman by putting up the little red flag that the 【mailbox】 contains letters to be picked up and mailed):

• A letter in his 【mailbox】 during his sophomore year of college started Dawayne on a journey that took him to Boston, then Hawaii.

2. = 【letter box】 3:

• Letters are collected from mailboxes located throughout the country, each posted with a sign that informs customers of mail pick-up times.

3. (Computers) the directory where computer stores messages:

• How do I change the display order of the messages in my 【mailbox】 ? I want the most recent items to appear at the top of my list.

See also: post box / post-office box.