The Penet remailer (anon.penet.fi) was a pseudonymous remailer operated by Johan "Julf" Helsingius of Finland from 1993 to 1996. It offered Internet users the ability to shield their identities when, for instance, posting messages to Usenet newsgroups. The Penet remailer was one of the first remailers, was very popular, and had a wide following. It also had some critics.
Several times, Helsingius was contacted by various people and individuals who wanted him to reveal the identities of certain people using the remailer to post anonymous messages. He was contacted once by the government of Singapore, as part of an effort to discover who was posting messages critical of the nation's government.
Helsingius refused all requests to reveal the identities of the users of his remailer, until the Church of Scientology used the legal system to force him to reveal the identity of one person who had posted a Scientology document to the newsgroup alt.religion.scientology in January of 1995. As part of its campaign against Internet users, Scientology obtained a court order, and police arrived at Helsingius' residence to seize the remailer. Initially he was asked to turn over the identities of all users of his remailer (which numbered over 300,000 at the time), but he managed a compromise and revealed only the single user being sought by the Church of Scientology.
In August 1996, a major British newspaper, The Observer, published an article accusing the Penet remailer of being used to post child pornography anonymously to Usenet newsgroups. This claim was proven to be false, because the remailer had an upper limit to the size of a file that could be posted through it. (The vast majority of picture files, including the claimed child pornography, were larger than the limit imposed by the remailer -- no more than 15,360 bytes or 15K.)
Helsingius successfully defended his remailer in court against the Church of Scientology's further attempts to obtain the identities of its users, but felt that the legal system in Finland would not, or could not, provide adequate protection against further legal attacks. As a result, he closed the remailer in September of 1996.
Because of the use of the legal system to attack the anonymity Penet offered to its users (and other attacks against anonymity elsewhere), more sophisticated anonymity networks were developed, like Type I Nymservers, of which not even the operator of the server can know the real identity of a pseudonym holder. This is made possible by using cryptography and anonymous remailers such as cypherpunk remailers and Mixmaster. The sender can create a chain of such remailers for a message so that no remailer can have access to information about both the sender and the recipient of the message.
- Helmers, Sabine (September 1997) A Brief History of anon.penet.fi - The Legendary Anonymous Remailer CMC Magazine.
- Post, David G. (April 1996). "The First Internet War". Reason Magazine (transcription).
- 1996 EFF press release concerning litigation against Helsingius
- Google archive of an144108's Usenet postings