Introduction

Spam relies on volume. Slowlists thwart that. If you throttle spam you can kill it, because spam's only selling point is high volume at high speed. The goal of slowlists is the complete elimination of spam from irresponsible ISPs by reducing it to an unprofitable level. It does not directly address spam ordinating from rogue users of otherwise good ISPs.

Slowlists restrict a sender's volume of email by delaying the receiver's response according to the reputation of (the IP address of) the sender. Senders in good grace move email without penalty; unknown senders are slowed, to provide a window to verify their volume; probable spammers are asked to retry later, to show their penance. This last delay can be calibrated to squelch even the huge number of open proxies. No email is ever rejected: only the patience of the sender is tried.

A sender's good reputation is shared with other good senders, to create a society of legitimate email movers. To be effective, a slowlists society should be large and communicate as if they were a single receiver, to throttle volume to any part of the society. Outsiders can still send mail -- slowly -- and over time gain the legitimacy they deserve.