North American Network Operators Group
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Re: marking dynamic ranges, was fixing insecure email infrastructure

  • From: Valdis.Kletnieks
  • Date: Tue Jan 25 12:23:43 2005 
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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