Pseudonymous remailer

A pseudonymous remailer, as opposed to an anonymous remailer, is an Internet software program designed to allow people to write anonymous messages on Usenet newsgroups and send anonymous email under a pseudonym. Unlike a purely anonymous remailers, it assigns its users a user name, and it keeps a database of instructions on how to return messages to the real user. These instructions usually involve the anonymous remailer network itself, thus protecting the true identity of the user.

Primoridal pseudonymous remailers once recorded enough information to trace the identity of the real user, making it is possible for someone to obtain the identity the real user through legal or illegal means. This form or pseudonymous remailer is no longer common.

David Chaum wrote an article in 1981 that described many of the features present in modern pseudonymous remailers. (Untraceable Electronic Main, Return Addresses, and Digital Pseudonyms; Communications of the ACM; Vol. 24; Number 2)

The most popular pseudonymous remailer was the Penet remailer, which lasted from 1993 to 1996.