Possible aid in filtering spam

[Ulf Zimmermann]

On Mon, Oct 31, 2005 at 08:40:33AM -0800, Ames Cornish wrote:
> On Sun, 2005-10-30 at 20:14 -0800, David Wolfskill wrote:
> > I then saw some machine say "HELO 63.192.123.122".  Ummm... no sale:
> > that's *my* IP address.  Added that to the filter, too.
> > 
> 
> David,
> 
> Thanks for the tip!  I just looked at my logs and I have quite a few
> spammers using my IP as the HELO.  None use the host name -- hmmmm.
> 
> Incidentally, I've been trying various anti-spam techniques on my
> mailserver, and collected statistics on the results.  I have a
> presentation on what worked best and what didn't here:
>    http://montebellopartners.com/slides/
> 
> Thanks for the info!
> 
> - Ames

I have started rejecting HELO using my IP a longer time ago. Then I went
actually a step further and rejecting any HELO with an IP. Much spam software
which are using comprised hosts, don't look up their hostname but just use
the IP number. As I interpret the RFC 821, HELO is to follow by the hostname
and a hostname is not an IP address. Yesterday my mail server rejected 6205
emails, 308 of those were based on HELO <IP>.

-- 
Regards, Ulf.

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Ulf Zimmermann, 1525 Pacific Ave., Alameda, CA-94501, #: 510-865-0204
You can find my resume at: http://seven.Alameda.net/~ulf/resume.html