By hiding IP addresses and other information from the recipient, it is possible to send e-mails that cannot be traced using Mixmaster. The idea of the service was to give users better protection from transparency.
However, an unknown person used Mixmaster to send a bomb threat to the University of Pittsburgh, prompting the FBI to seize the server to try to find out who was behind the threat.
According to both ISPs, it is unlikely that the FBI will be able to trace the user as Mixmaster does not save any log files that can be used to trace the sender.
– This is an extrajudicial punishment and an attack on freedom of expression. It can be used as a deterrent example for other providers that offer anonymous services on the Internet, Riseup Networks writes in a statement.