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

Brandon Long <> Wed, 02 December 2020 02:22 UTC

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From: Brandon Long <>
Date: Tue, 1 Dec 2020 18:21:51 -0800
Message-ID: <>
To: Michael Thomas <>
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Subject: Re: [dmarc-ietf] A policy for direct mail flows only, was ARC questions
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On Tue, Dec 1, 2020 at 10:07 AM Michael Thomas <> wrote:

> On 11/30/20 8:56 PM, Brandon Long wrote:
> Right, some of the other dkim-light or diff concepts we discussed would be
> better than using l=
> We again got hung up on the 100% solution, though... something that
> handled subject-prefix and
> footer in a transport agnostic way might have worked.  The fact that DKIM
> isn't transport agnostic
> is an achilles heel to even that, though, since we'd have to come up with
> a new canonicalization
> and get it to widespread adoption before the simple diff could work.  Or
> require mailing lists to
> be a lot more strict in how they do their email rewriting, but I imagine
> that's harder work than
> even ARC.
> Frankly all it would take is a google or another large mail provider to
> publicly state that unless a mailing list supports BCP XYZ, your mail will
> be subject to very strict scrutiny and likely not delivered to get the
> attention of mailing list providers. That was my suggestion back in the day
> but it was scoffed at because people could point to some edge case that
> generates .001% of list traffic and thus invalidating the entire approach.
> The best is definitely the enemy of the good here.
> People really need to keep in mind that service provider email is not the
> only game in town. That point keeps getting lost.
arguably we're all here because a large mail provider did make such a
change (though to be fair, there were plenty of others who wanted to make
that change).

While Google might be able to help move things along, there would need to
be strong community support for that, no one wants to go this alone and
look like the big bully.

I also think that you're overestimating what we could do.  Ultimately, we
serve our customers, and they want their legitimate email, even if it
doesn't support BCP XYZ.