-----Original Message-----
From: asrg-bounces(_at_)ietf(_dot_)org
[mailto:asrg-bounces(_at_)ietf(_dot_)org] On Behalf Of
Markus Stumpf
Sent: Tuesday, April 12, 2005 1:09 PM
To: George Ou
Cc: asrg(_at_)ietf(_dot_)org
Subject: Re: [Asrg] article: port 25 blocking
On Mon, Apr 11, 2005 at 11:37:05PM -0700, George Ou wrote:
* Start banning all non-SPF compliant domains within a certain
deadline which would effectively make port 25 blocking moot.
Sorry, this is not how SPF works.
Says who? SPF blocks all hosts that are not registered as SMTP servers in
their domain's authoritative DNS servers. That DOES make blocking consumer
outbound 25 moot.
Nothing prevents a spammer from getting throwaway domains, adding TTL 300
SPF records and using some 10000 cracked hosts on broadband access to spam.
I never claimed SPF stops spammers from using stolen SMTP credentials. This
same issue applies to port 25 blocking as well. SPF does make it possible
to block abusive or irresponsible domains.
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