-----Original Message-----
From: asrg-bounces(_at_)ietf(_dot_)org
[mailto:asrg-bounces(_at_)ietf(_dot_)org] On Behalf Of Bill
Cole
Sent: Tuesday, April 12, 2005 3:26 PM
To: asrg(_at_)ietf(_dot_)org
Subject: RE: [Asrg] article: port 25 blocking
Have you looked at how port 25 blocking is actually being done by even the
minimally competent ISP's? SBC is an example of one such. 8 months ago they
had a press release and sent mail to all customers about the coming rollout
of port 25 blocking. With that they included a way to preemptively request
exemption and they made clear that customers with static address accounts
would be excluded by default.
To my profound shock, SBC has actually managed to execute that rollout with
reasonable speed and accuracy. There may well be some ISP's who are
implementing port 25 blocking without exempting users with static IP
assignments, but I believe they would be the minority.
SBC's willingness to provide exceptions for anyone who asks may be unusual,
but it is not unique.
You're always free to implement port 25 blocking on your side for inbound
traffic which effectively achieves the same thing for your network. You
just need to implement a large ACL yourself that might be synchronized with
a large shared database somewhere on the net. Why do you want everyone else
to implement outbound port 25 blocks for you?
Bottom line is, you'll have the same problem convincing people to block
outbound 25 as you will convincing them to implement SPF. SPF just happens
to be a better solution in my opinion.
George
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