Yes, I remember IBM had its own email system back in the early 80's when I worked there, AT&T had its own in the later 80's. Even Prodigy/Compuserve/AOL had pro

Yes, I remember IBM had its own email system back in the early 80's when I worked there, AT&T had its own in the later 80's. Even Prodigy/Compuserve/AOL had proprietary email systems (IIRC) with internet email bolted on. And getting email to the internet at large was no mean feat: I remember having to do a slew of UUCP addressing to get an email from AT&T to the internet (something along the lines of "astevens@redhill3!ihnp4@mit.edu). It was the wild west.