Cypherpunk anonymous remailer

A cypherpunk anonymous remailer, also known as a Type I remailer, is a type of anonymous remailer that receives messages encrypted with PGP or GPG, follows predetermined instructions to strip any identifying information, and forwards the messages to the desired recipient.

Cyberpunk anonymous remailers are susceptible to traffic analysis attacks, exploiting the fact that messages sent to such remailers are all then sent to the recipient in the order they were received, making it possible to identify who sent which message. This weakness has motivated the development of Type II and Type III remailers. Before Mixmaster or Type II remailers, a solution to this problem was to send mail in batches; alternatively, multiple remailers could be used in sequence to further obfuscate the sender's identity.

When Type II remailers came into existence, they built upon the technology of Type I remailers. This made Type I remailers mostly obsolete. However, there are still websites and systems that rely on this general idea of layered encryption and identity obfuscation.[6]