A pseudonymous remailer or nym server, 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 of 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 Mail, Return Addresses, and Digital Pseudonyms; Communications of the ACM; Vol. 24; Number 2)

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

Contemporary Nym Servers

A nym server (short for "pseudonym server") is a server that provides an untraceable e-mail address, such that neither the nym server operator nor the operators of the remailers involved can discover which nym corresponds to which real identity.

To set up a nym, one creates a PGP keypair and submits it to the nym server, along with instructions (called a reply block) to anonymous remailers (such as Cypherpunk or Mixmaster) on how to send a message to his real address. The nym server returns a confirmation through this reply block. He then sends a message to the address in the confirmation.

To send a message from the nym, one adds a few headers at the beginning, then signs it with his nym key and encrypts it to the nym server key. He sends it to the nym server, normally through anonymous remailers so that it cannot be traced. The nym server then sends it out, with the From: address being the nym.

When the nym server gets a message addressed to the nym, it appends it to the reply block for that nym and sends it to the first remailer in the chain. That remailer then sends it to the next, and so on until it reaches the user's real address. It is good practice to add instructions to encrypt it on the way, so that the message one gets cannot be matched to the one the nym server sent.

See Also

• Nym server