[77563] in North American Network Operators' Group
Re: marking dynamic ranges, was fixing insecure email infrastructure
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Tue Jan 25 12:23:02 2005
To: Markus Stumpf <maex-lists-nanog@Space.Net>
Cc: Suresh Ramasubramanian <ops.lists@gmail.com>, nanog@nanog.org
In-Reply-To: Your message of "Tue, 25 Jan 2005 18:03:02 +0100."
<20050125170302.GV62086@Space.Net>
From: Valdis.Kletnieks@vt.edu
Date: Tue, 25 Jan 2005 12:22:33 -0500
Errors-To: owner-nanog-outgoing@merit.edu
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On Tue, 25 Jan 2005 18:03:02 +0100, Markus Stumpf said:
> How did you calculate that "40% of my legitimate email"?
> If you get 60 emails from 60 different hosts that have revDNS and you
> get 40 mails from two hosts without revDNS then also "40% of your
> legitimate email" is coming from servers without revDNS, but in fact
> the precentage of servers without revDNS would be around 3.2%. Quite
> a difference.
Which would mean that if Suresh insisted on revDNS, he'd end up blocking
only 2 hosts, but 40% of his legitimate mail would be dropped on the floor.
I'd *hope* that knowingly dropping 40% of the *legitimate* mail on the floor
would be considered a CLM. But these days some providers seem to think
"all of Europe" is a reasonable filter.....
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