Mixminion is a message-based anonymous remailer protocol intended to take the place of the old Mixmaster network. Mixminion provides secure single-use reply blocks (Mixmaster provides no support for replies, instead relying on the older and less secure Cypherpunk remailers), and introduces nymservers that allow users to maintain long-term pseudonyms using single-use reply blocks as a primitive. It also integrates directory servers that allow users to learn public keys and performance statistics of participating remailers. I'll cover a variety of serious anonymity issues with Mixmaster and other deployed networks and published designs, and also describe some of the many surprising anonymity risks that come from adding these new services.