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

Michael Thomas <mike@mtcc.com> Sat, 05 December 2020 18:37 UTC

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From: Michael Thomas <mike@mtcc.com>
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Date: Sat, 5 Dec 2020 10:37:37 -0800
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Subject: Re: [dmarc-ietf] A policy for direct mail flows only, was ARC questions
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On 12/5/20 10:29 AM, John Levine wrote:
> In article <CABa8R6spYyZDhzEnQ=txdoLOO1Ek1MAryW6ioAsur1_mEvdXkA@mail.gmail.com> you write:
>> mailing list to mailing list mail is very common in GSuite, but maybe we're
>> a special case.
> I dunno how special that case is, but there are lots of cases where mail passes
> through multiple layers of ARC signing mutations.
>
> I routinely get mail from Microsoft's farm with an ARC seal or two
> that has never been near a mailing list. Any time a MS user sends a
> message to one of my lists, it'll emerge with at least two ARC
> signatures.

Getting multiple signatures from the originating domain doesn't hurt 
anything. It's a little wasteful, but that's it.

Mike