It was probably created during or shortly after the period of prohibition in the United States of America or on Cuba, i.e. in the 1920s or 1930s.

As with the slightly older Aviation cocktail, to whose recipe there is no similarity, the name is reminiscent of aviation which developed rapidly at that time. In those years when international telephone connections were still a rarity, airmail was the fastest means of communication across national borders. Because of prohibition, Americans were only able to legally drink alcohol abroad until 1933. Cuba, among other countries, benefited from this as a pronounced bar and cocktail culture began developing on the island in the 1920s. Since 1925, flights were available from Key West to Havana,^[2] and in 1930, a regular airmail service was established to and from the island.^[3] Shortly after, the Airmail Cocktail appeared for the first time in an advertising brochure of the then still Cuba-based rum manufacturer Bacardí.^[3]

In 1941, the recipe was published in a mixology book.^[4] In his recipe collections, Just Cocktails (1939) and Here’s How (1941), the author W.C. Whitfield had collected numerous drinks from the years of prohibition and provided them with comments partly in laconic style. As far as the Airmail Cocktail is concerned, Whitfield commented on it ‘It ought to make you fly high’.^[5] The cocktail gained further popularity when the recipe was mentioned in the Handbook for Hosts in Esquire magazine in 1949.^[6]

In the following decades, the cocktail wasn’t very popular, having been published rarely. In the 2010s, however, the cocktail experienced another boom by being mentioned in the ‘PDT Cocktail Book’ (2011) and by the promotion of alcoholic drinks by the brand Bacardí.^[7]

Référence: https://en.wikipedia.org/wiki/Airmail_(cocktail)

Référence : https://www.diffordsguide.com/cocktails/recipe/27/air-mail