nanog mailing list archives

Re: The End-To-End Internet (was Re: Blocking MX query)


From: Greg Ihnen <os10rules () gmail com>
Date: Wed, 5 Sep 2012 11:46:34 -0400

On Wed, Sep 5, 2012 at 11:11 AM, Izaac <izaac () setec org> wrote:

On Wed, Sep 05, 2012 at 07:50:12AM -0700, Henry Stryker wrote:
Not only that, but a majority of spam I receive lately has a valid DKIM
signature.  They are adaptive, like cockroaches.

This is why tcp port 25 filtering is totally effective and will remain so
forever.  Definitely worth breaking basic function principles of a
global communications network over which trillions of dollars of commerce
occur.

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But as someone pointed out further back on this thread people who want to
have their mail servers available to people who are on the other side of
port 25 filtering just use the alternate ports. So then what does filtering
port 25 accomplish?

Greg


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