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Re: Misguided SPAM Filtering techniques
On Sun, 21 Oct 2007, Nathan Ward wrote: > > http://www.ietf.org/rfc/rfc2476.txt Note that this has been superseded by RFC 4409. More recommendations about the operational and policy issues are laid out in http://www.ietf.org/internet-drafts/draft-hutzler-spamops-08.txt which will soon be published as RFC 5068. Sadly it doesn't say much about the rationale for its recommendations, especially why it's not OK to block 587 even when it might be OK to block 25, because talk of port blocks rapidly descends into flame wars. However it's fairly clear if you think about who suffers from spam sent via port 587. The key point is that the operators of an MSA has a strong incentive to keep their users clean, or at least their mail flows clean, because any spam sent via their MSA will (typically) go out of the same relays whether the client is on site or roaming or using the webmail service. Therefore reputation problems (AOL spam complaints, blacklistings, etc.) will accrue where it hurts. The situation is very different for port 25 email, becase the target MTA has no control over the senders. Access providers don't care about their access networks having bad spam reputations because the pain doesn't affect them directly enough. Tony. -- f.a.n.finch <[email protected]> http://dotat.at/ SOUTHEAST ICELAND: NORTHERLY 5 AT FIRST IN EAST, OTHERWISE SOUTHEASTERLY 4 OR 5 INCREASING 6 OR 7. MODERATE OR ROUGH. RAIN LATER. GOOD, OCCASIONALLY MODERATE LATER.