On Friday 26 November 2004 03.34, Stephen Frost wrote: > * Adrian 'Dagurashibanipal' von Bidder (avbidder@fortytwo.ch) wrote: > > <plug> > > And, of course, postgrey as the very first line of defense. > > </plug> > > Coupled with the usual checking on HELO (blocking 'localhost' HELOs and > > my own IP does wonders!), SMTP protocol conformance (pipelining), > > sender (envelope) address checking. > > Things which increase the load on the remote mail servers are *bad*. > That would include responding with temporary errors unnecessairly and > adding unnecessary delays in communication. pipelining by itself isn't > necessairly terrible- adding things like 2 minute delays is bad though. I'm happy to queue my outgoing email if the remote end uses greylisting, as I expect the remote site to queue my incoming mail with my greylisting. Add to the the fact that amongst the mail senders big enough so that the queue size matters are probably many of those ISPs with badly policed (DSL/cable) network, operating the spam zombies which cause me to use greylisting in the first place... About pipelining: what postfix does is enforce proper use of pipelining: the sender may only start pipelining requests when it has actually seen that postfix does support pipelining. Regular mail servers never notice this, but some stupid spammers just push the request out without waiting for responses at all - these are rejected. -- vbi -- TODO: apt-get install signify
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