An important early RFC from the IETF that specified the format of e-mail messages exchanged between computers on the Internet. Many additions have been made to it, but it remained a standard for many years until obsoleted by RFC 2822 (the number is not a coincidence: it was reserved for this use).
... the census of 2000, there are 19,701 people, 6,700 households, and 5,011 families residing in the town. The population density is 1,549.2/km² (4,010.1/mi²). ...