I bet that spoofed email came from a residential dialup. If my stats are representative of anything, it's most likely to have come from, in order of frequency:

  1. comcast.net
  2. ameritech.net
  3. pacbell.net
  4. attbi.com
  5. swbell.net
  6. rr.com
  7. optonline.net
  8. charter.com
  9. shawcable.net
  10. dsl-verizon.net

Refusing email from dialups (but accepting from the official MTA of the ISP) results in a dramatic reduction in spam.

There are other ways of reducing spam from within the existing RFC-2821 framework. Adding yet another DNS hack is never going to succeed. For instance, in an ideal world, one would only accept connections from a host whose IP address has matching forward and reverse DNS resolutions. And the HELO/EHLO string would exactly match one of those resolutions.

This is easy for a competent sysadmin to set up (although it is depressing beyond belief to observe how many domains don't get these simple basics right). Spammers do so many stupid random things with the message envelope that just correlating the HELO with the resolved client name would blow them out of the water.

And if they did start doing the right thing (in the RFC sense of the term) it would be trivial to identify them and hence blacklist them.

SPF is bogus, stop spreading the idea that it will resolve the spam problem.

In reply to Re: SPF for Perl Monks domains (no no no) by grinder
in thread SPF for Perl Monks domains by Juerd

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