I just spent the whole day upgrading/hacking Cyrus for inserting proper Return-Path:-headers just to make Sieve's reject work... Part of my ~/.sieve now contains elsif allof (address :contains "to" ["[EMAIL PROTECTED]","[EMAIL PROTECTED]"], header :is "subject" "unsubscribe") { reject "please visit http://www.amanda.org/ for instructions how to unsubscribe from [EMAIL PROTECTED]"; } Hopefully people will get to know how to unsubscribe.