Re: [dmarc-ietf] Ticket #111 - MX/A/AAAA test needs justification

Douglas Foster <> Fri, 07 May 2021 03:13 UTC

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From: Douglas Foster <>
Date: Thu, 6 May 2021 23:13:22 -0400
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Subject: Re: [dmarc-ietf] Ticket #111 - MX/A/AAAA test needs justification
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This is about
Section 3.8. Non-existent Domains

   For DMARC purposes, a non-existent domain is a domain for which there
   is an NXDOMAIN or NODATA response for A, AAAA, and MX records.  This
   is a broader definition than that in [RFC8020].

My argument is that that A/AAAA/MX has no useful relevance to
determining whether the RFC5322.FROM address of a message should be
evaluated based on SP or NP.  NP is described as testing
"non-existent", rather than "possibly able to receive mail".   We need
a test that evaluates whether the domain exists or not, and is
maximally protected from false positives caused by host names and

If this group is convinced that A/AAAA/MX is meaningful for the
distinction between SP and NP, I am asking someone to provide the
justification and define the algorithm.  Right now I have seen

On Thu, May 6, 2021 at 9:52 PM Seth Blank <seth=> wrote:

> On Thu, May 6, 2021 at 18:47 John Levine <> wrote:
>> It appears that Douglas Foster  <>
>> said:
>> >My perception has been that NDRs are widely ignored even when they are
>> >sent.  Is your experience different?
>> Yes.  We are not going to rewrite RFC 5321 here.  Please stop.
> Doug, I don’t understand what textual consideration within the DMARCbis
> documents you are discussing.
> Please reference the text in question and your proposed modifications, or
> move on to a topic which is material to driving this bis documents to
> completion, which is our current work item.
> Seth, as Chair
> --
> *Seth Blank* | VP, Product
> *e:*
> *p:* 415.273.8818
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