> Kevin Chadwick wrote: > > On Wed, 30 May 2012 13:00:45 -0400 > > Kurt Mosiejczuk wrote: > > >> That's also why spamd in greylisting stutters for the first 10 seconds. > >> Many spammers disconnect now when stuttered at, so they give up before > >> even starting the greylisting process. > > > It might be now. I believe the original reason was to tie up > > more spammers resources than your own. > > That's why the blacklist mode stutters. It's a tarpit. Originally > greylisting didn't stutter. > > http://www.openbsd.org/papers/bsdcan05-spamd/ > > In particular, this slide: > > http://www.openbsd.org/papers/bsdcan05-spamd/mgp00017.html
It was discovered quite early on that spammers were using something like: write a line to the socket (wait up to 5 seconds for the response) (not finished yet? give up -> disconnect) (move on to the next target)
