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Re: [dmarc-ietf] auth-res vs. dmarc

Alessandro Vesely <vesely@tana.it> Wed, 30 December 2020 19:38 UTC

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From: Alessandro Vesely <vesely@tana.it>
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Date: Wed, 30 Dec 2020 20:38:43 +0100
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Subject: Re: [dmarc-ietf] auth-res vs. dmarc
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On Wed 30/Dec/2020 16:17:21 +0100 Michael Thomas wrote:
> 
> On 12/30/20 7:06 AM, Laura Atkins wrote:
>> The auth-res result posted as an example of DMARC failing earlier in this 
>> thread:
>> Authentication-Results:mx.google.com;
>>         dkim=passheader.i=@ietf.org  header.s=ietf1 header.b=aayvF8Pg;
>>         dkim=passheader.i=@ietf.org  header.s=ietf1 header.b="PwU4/yuQ";
>>         dkim=neutral (body hash did not verify)header.i=@mrochek.com  header.s=201712 header.b=PRr8Q7Zv;
>>         spf=pass (google.com: domain ofdmarc-bounces@ietf.org  designates 4.31.198.44 as permitted sender)smtp.mailfrom=dmarc-bounces@ietf.org;
>>         dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=mrochek.com
>> The policy statement is right there: p=NONE.
>>
> No. That is not guaranteed whatsoever. It could say "(eat at Joe's)" and be valid.


Correct.  However, it could have been:

     dmarc=fail policy.dmarc=none header.from=mrochek.com

where the property meaning is defined as "Evaluated DMARC policy applied/to be 
applied after policy options including pct: and sp: have been processed. Must 
be none, quarantine, or reject."

That value appears on the IANA page[*] referring to RFC7489 for its definition. 
  However, Section 11.1 of RFC 7489 only mentions the "from" property.

IMHO, dmarc=quarantine is more direct than dmarc=fail policy.dmarc=quarantine.

In addition, policy.dmarc as a ptype.property pair sounds redundant.  Perhaps 
it should be policy.result, to emphasize that it has been computed after 
checking pct= and sp= (to be added: np=) and the alignment of header.from with 
respect to the dns zone where the record was found.

Best
Ale
-- 

[*] https://www.iana.org/assignments/email-auth/email-auth.xhtml

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