Majordomo

LISTSERV was commercial and lived on BITNET. In 1992 Brent Chapman, then at Great Circle Associates, wrote Majordomo in Perl to run mailing lists on ordinary Unix machines. You emailed subscribe listname to majordomo@host, and the program added your address, sent a confirmation and handled moderation, digests and archives.

Through the 1990s Majordomo sat behind a large share of the internet's mailing lists, especially technical and academic ones. It was administered by email, with the list owner's password sent in plain text. GNU Mailman, with a web interface, took over from the late 1990s and Majordomo development stopped. The misdirected "unsubscribe" sent to the entire list, however, survived the transition intact.