bduncan writes "RFC-821 and the sister RFC-822 are 30 years old this month. Remembering back to times when it was common to see teletypes for *fast* interoffice communication and a huge email (if you had access) might be anything over 5K." Link to Original Source
Time-sharing is the junk-mail part of the computer business.
-- H.R.J. Grosch (attributed)