Douglas Harper's Etymology Dictionary
Wiktionary
alt. mail transported by aircraft. n. mail transported by aircraft.
WordNet
n. mail that is sent by air transport [ant: surface mail]
Wikipedia
Air Mail is a 1932 American Pre-Code adventure film directed by John Ford, based on a story by Dale Van Every and Frank "Spig" Wead. The film stars Ralph Bellamy, Pat O'Brien and Gloria Stuart. A copy is preserved in the Library of Congress.
Air Mail is an album by the improvisational collective Air featuring Henry Threadgill, Steve McCall, and Fred Hopkins recorded for the Italian Black Saint label. The album consists of three compositions dedicated to Bobbie Kingsley, Ronnie Boykins, and Cecil Taylor & Jimmy Lyons.
Air Mail is an iOS game developed by Chillingo Ltd and released on May 24, 2012.
Usage examples of "air mail".
It was, he saw, an air mail sheet and was postmarked London and the return address bore a name that was unfamiliar to him.
It was, he saw, an air mail sheet and was postmarked London  .
In fact, I know you will, because I shall write air mail, and she's certain to write air mail to you.