used in computer message shorthand to mean “for your information” US,1991
[S]he will hand me a bowl of rice pudding, indicate the whipped cream with a spy’s nod, and murmur, “FYI, friend.” — Ethan Morden, EverybodyLovesYou, p. 136, 1988
— Eric S. Raymond, TheNewHacker’sDictionary, p. 342, 1991