Re: [dmarc-ietf] ARC vs reject

Hector Santos <hsantos@isdg.net> Sun, 06 December 2020 03:51 UTC

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Date: Sat, 05 Dec 2020 22:51:44 -0500
From: Hector Santos <hsantos@isdg.net>
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Organization: Santronics Software, Inc.
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To: Michael Thomas <mike@mtcc.com>, dmarc@ietf.org
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Subject: Re: [dmarc-ietf] ARC vs reject
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On 12/5/2020 5:07 PM, Michael Thomas wrote:
>
> On 12/5/20 2:02 PM, John Levine wrote:
>> OK, ARC doesn't do that. This does not mean that ARC is broken, only
>> that you appear to have different policy priorities than other people.
>> As you know, DMARC has never obliged recipients to follow senders'
>> policies so this is nothing new.
>
> If ARC is advocating for a bypass of p=reject that introduces a new
> state. If my policy is reject, I want you to reject the mail. If I
> want you to reject the mail unless you think it has come from an
> acceptable place with receipts, then you need a new policy tag like
> reject-except-valid-arc.

I have long suggested one way to resolve this is by using a new DMARC 
extended "arc=" switch.  Allow the author domain define what is 
acceptable from an ARC standpoint, if interested.

arc=N   where N is the arc seal count, whatever amount is allow to 
"promote" a failed DKIM to a pass.  The inherent default arc=0 would 
suggest arc should not be a consideration DKIM fails.

In principle, I am for using DMARC extended switches to outline the 
different protocol behaviors.

arc=1  DMARC Receiver MAY consider using arc for failure promotion

atps=1  DMARC MAY consider using RFC6541

rewrite=0 Mailing List SHOULD NOT rewrite 5322.From

Keep it simple folks.

-- 
Hector Santos,
https://secure.santronics.com
https://twitter.com/hectorsantos