Re: [dmarc-ietf] A policy for direct mail flows only, was ARC questions

John Levine <johnl@taugh.com> Wed, 25 November 2020 20:31 UTC

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Subject: Re: [dmarc-ietf] A policy for direct mail flows only, was ARC questions
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In article <b0f72407-81ce-9990-4a5b-7b0e5b76e3d7@mtcc.com>om>,
Michael Thomas  <mike@mtcc.com> wrote:
>When I was at Cisco, with l= and some subject line heuristics I could 
>get probably like 90+% verification rate across the entire company, a 
>company that uses external mailing lists a lot. Definitely not 100% though.

I think you will find that at very large mail systems like gmail and
Microsoft and Yahoo, 90% might as well be 0%. The volume of errors is
just too high and the number of complaints would be impossible.

While I almost never see the sort of spam leakage through mailing lists 
that Brandon reports, I believe him when he says it's enough of a problem
that Gmail can't just whitelist traffic from mailing lists.

R's,
John
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John Levine, johnl@taugh.com, Primary Perpetrator of "The Internet for Dummies",
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