RE: [NTISP] Spam Filtering

Kurt A. Butzin ( (no email) )
Sun, 7 Mar 1999 12:18:03 -0500

I believe that using reverse lookups for e-mail delivery is in violation of
the RFC, but I not for sure on it. If so, this is going to cause some
resistance to using it in some corporate IS departments.

> -----Original Message-----
> From:
> []On Behalf Of David Payer
> Sent: Sunday, March 07, 1999 8:43 AM
> To:
> Subject: Re: [NTISP] Spam Filtering
> >As for reverse DNS, the only thing I have seen where it is even remotely
> >useful is for companies who use a reverse lookup in conjunction with a
> whois
> >trace to determine whether or not you are eligible to download a strong
> >encryption product. And even then, all one needs is a shell
> account in the
> >U.S. to get around that.
> >
> You are correct that those who know how to can easily bypass the issue of
> screening against reverse lookups. But my point is this: the MAJORITY of
> spam comes from those marketers who want to find a quick way to send out
> multiple thousand emails. I did a review of logs for rejected
> addresses and
> tested many by telnetting back to port 25. Over 95% of those
> tested did not
> respond on that port. For the more dedicated spammers, the Real Time
> Blackhole List filters will be helpful.
> My problem when I do filtering is that some corps use firewalls
> and don't do
> inverse addressing and then their workers send mail back to their home
> account on our service and we reject it due to inverse addressing
> filters. I
> find that there are administrators who will reject you out of
> hand regarding
> setting up their network with this one precaution.
> I again assert, if we don't make efforts to stop spam ourselves, we will
> have governmental assistance in doing that. This will come with an
> accompanying tax to pay for administrating it. Once that mechanism is in
> place, the influence will grow (remember: income tax was
> originally never to
> exceed 3%).
> OK </republican-jargon>
> David Payer
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