There are several different types of problem messages, and some are easier to avoid than others. - Spam - Harassing messages sent to remailer users - Harassing messages sent to mundanes to annoy the mundane - Harassing messages sent to mundanes to get the remailer in trouble - Harassing messages sent to third-parties (e.g. sending Bob slander about Alice.) - Forged messages - Usenet flamebait Two of the things I never built back when I was running a remailer could have helped this problem - Encrypted-sending only. Sure, you want to only accept encrypted messages to preserve privacy, but if you require outgoing messages to be encrypted, you not only protect privacy, you eliminate most of the spam, except for spam that's sent to people with easily-located public keys. Sadly, that's a small set of people, but it's also tougher for harvester programs, and it's a set of people less likely to buy from spammers. This also significantly reduces harassment potential. Most crypto users are more likely to understand remailers, or at least to read the "this is a remailer" headers. It's possible for harassers to work around this, if you're verifying encryption just by syntax, but it's a good start: ----- BEGIN PGP ENCRYPTED STUFF Alice - your mother was a hamster and your father smells of elderberries. And your hovercraft is full of eels. Bob ----- END PGP ENCRYPTED STUFF --- - Recipient permission for outbound remailers - have the remailer ask for permission before sending somebody mail, and optionally store addresses (or hashes of addresses) of people who want to accept remailed messages in the future (obviously including other remailers in that list.) So instead of sending the message directly, you send "Subject: You've received an anonymous message #1234567 You've received an anonymous message at (foo-remailer) It may be from someone you know, or may be a forgery or spam (explain remailers blah blah blah) If you'd like to pick up the message, reply to this message. If you don't want it, just ignore this message. If you'd like us to never bother you again, reply with Subject: BLOCK If you'd like to automatically receive all remailer messages in the future, reply with Subject: SUBSCRIBE (and/or provide web URL interfaces for these functions.) Even if the remailed mail is spam or harassment, it starts out with getting permission from the recipient and building a positive relationship and some understanding of what's going on. It also means that if somebody who doesn't care about remailers gets spam or harassing mail, they don't have to get it more than once. Bill Stewart bill.stewart@pobox.com