Fun trivia: in the early days of the ARPAnet, mail was delivered (at least on PDP-10's) by FTP-appending a message in to the receipients mailbox file. (Which was protected as append-only to world (owner, group, world).)
Didn't last long, obviously, but that was back in the days when every site had a well-publicized guest login and you could telnet anywhere. (Well, OK, in 1972 there were only a few dozen nodes, but there were some really interesting ones to play with.)
We used to play a game with telnet from HARV-10 where we'd telnet-chain around the world until someone dropped the connection or it got too slow.
Back in the days of X.25 and the UK "coloured book" protocols, grey book email went over blue book "network independent FTP" (in batch). I don't know how NIFTP compared with ARPANET FTP as a protocol, though.
Didn't last long, obviously, but that was back in the days when every site had a well-publicized guest login and you could telnet anywhere. (Well, OK, in 1972 there were only a few dozen nodes, but there were some really interesting ones to play with.)
We used to play a game with telnet from HARV-10 where we'd telnet-chain around the world until someone dropped the connection or it got too slow.