Cypherpunk anonymous remailer

A Cypherpunk anonymous remailer is an anonymous remailer that takes messages encrypted with PGP or GPG, or in some cases in plain text, and remails them. The message is preceded with the following pseudoheader (called "pseudoheader" because it is after the RFC 822 headers):

Request-Remailing-To: final@destination.net

then encrypted to the remailer's key, and the following pseudoheader is prepended to the result:

Encrypted: PGP

Some Cypherpunk remailers are also Mixmaster anonymous remailers and can split long Cypherpunk messages into Mixmaster packets and send them to the next remailer, if it also understands Mixmaster.