The history of email entails an evolving set of technologies and standards that culminated in the email systems in use today.
https://github.com/davepinch/pinchy.cc/blob/master/content/topics/computing/history-of-email/en.wikipedia.org.md
SNDMSG (Wikipedia) SNDMSG was an early electronic mail program, chiefly notable because it was used to send what is considered the first networked email.
