oPlease

First scented messages sent across the Atlantic - CBS News

"The photo plus odor message is…sent via email, text, or tweet to the recipient, who can receive the scented 'oNote' on a specially-designed device called an oPhone."

I don’t know if they were ever adapted to Air Mail (no, boys and girls, you don’t remember Air Mail; put your hands down) but receiving a scented note from one’s girlfriend was once (a very, very long time ago) both fairly common (it happened to every guy sooner or later) and, generally, the cause of great merriment (especially if received in a barracks). And no oPhone was required.