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Re: new spam filtering rule

2005-06-28 11:46:10
At 14:05 2005-06-28 +0200, Ruud H.G. van Tol wrote:
Professional Software Engineering schreef:

> Comments anyone (besides arguing about specific tlds, which are a
> matter of preference)?

And most spam here is From *.com and contains common English words.

I realize most spam is from .com, but the point is that many .com users may not generally receive a lot of mail from .xx, and therefore, that small segment of their spam can be better classified as iffy by inclusion of this check. No single check is going to thwart all spam.

IP-to-country DNS mapping service:
  http://countries.nerd.dk/

I'm operating on the email addresses. The TLDs used often bear no relationship to the origin IP. Examining just a small number of recent messages, I see .es and .nl coming from korean IP space, .ch from verizon (in the US), .au from alltel (in the US). Of the handful I just checked, not a one comes from IP space even remotely connected with the country the message is claimed to be from. I already block several Asia-Pacific origins via a DNSBL I created (before things like nerd.dk came into existance), and it works quite well for keeping out a lot of unwanted stuff, which by merit of being rejected during the SMTP RCPT phase, I don't have to waste processor time on.

I guess one could cross reference the sender TLD and the IP space the message was relayed via, though ISPs hosting in multiple countries (esp. within Europe) could pose issues.

---
 Sean B. Straw / Professional Software Engineering

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