Great to hear that people are having success with greylisting. Just what I was hoping to hear. I've just turned it on. I'm using milter-greylist for sendmail with a 10 minute threshold to start with. Will be interesting to see the results.
Just saw some traffic on the MIMEDefang list about new features in sendmail 8.13 that can help deal with proxy spammers, like the greet_pause feature.
