Re: [Asrg] Re: SPF abused by spammers

[Daniel Feenberg <feenberg at nber.org>]

On Tue, 14 Sep 2004, Markus Stumpf wrote:

> 
> > SPF will allow them to limit these without having to resort to
> > expensive, difficult and time consuming network changes.
> 
> Could you explain this a bit more in detail? How could a ISP use
> SPF to limit port 25 connections?
> 
> 	\Maex

I have another question - Even given that an ISP might not want to close
port 25 outbound from its dynamic address customers at the router level,
what advantage does SPF have over merely informing MAPS/Spamhaus, etc of
its dialup ranges? Those services already exist and are widely used,
while SPF is in infancy. Notice I ask what advantage, not what difference,
as I realize that in one case the authorization is by the IP address
ownership, and in the other by domain name ownership. In this discussion,
however, both have been owned by the same party (the ISP, $D).

The only way I can understand SPF is as a way to distinguish spam from
non-spam on a single sending MTA. If the ISP thinks a host sends only
spam, aren't there are easier ways to deal with the situation?



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