I read about some changes that John Perry made to his remailer, since it is being abused. (Sorry to hear it!) I thought he said he is doing source blocking (I deleted the message and can't check.) Is this true? Were there no hops between the abuser and the remailer? How can you prevent the abuser from just chaining through different paths to reach your remailer and continuing to use it? Or am I remembering incorrectly ;) Random Factor suggested (among other things)
* require encryption for incoming messages.
Requiring encryption is OK, as long as you don't require the remailing header and message body to be encrypted together. If you do, like the extropia remailer does, then you can't form reply blocks that include such a remailer (since the reply block is created by a sender who obviously doesn't have the message body that his recipient will use the reply block to respond to).