Re: [dmarc-ietf] Ticket #1 - SPF alignment

Scott Kitterman <sklist@kitterman.com> Wed, 10 February 2021 14:43 UTC

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From: Scott Kitterman <sklist@kitterman.com>
To: dmarc@ietf.org
Date: Wed, 10 Feb 2021 09:43:04 -0500
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Subject: Re: [dmarc-ietf] Ticket #1 - SPF alignment
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No.  Sigh.  Let's try it again.

Yes, one might actually use a HELO result for DMARC.  It gives you the same 
result as if mail from is null.  So what?

No one has given us a case where an attacker could get a aligned SPF result 
based on HELO that they couldn't also get with mail from, so it doesn't 
matter.

By problem, I mean an actual problem.  There aren't any.

Scott K

On February 10, 2021 9:49:46 AM UTC, Alessandro Vesely <vesely@tana.it> wrote:
>Just to clarify:
>
>
>On Wed 10/Feb/2021 05:19:38 +0100 Scott Kitterman wrote:
>> No one has demonstrated that if someone has implemented SPF (RFC
>7208) without
>> worrying about DMARC that there are any associated problems for
>DMARC.
>
>
>I think I did.  OpenDMARC, for example, seems to read a single result,
>either 
>Authentication-Results: or Received-SPF:, assuming that it contains the
>mfrom 
>identity unless empty.  Note that it has an option to disable SPF
>entirely, 
>presumably as a means to tackle non-DMARC oriented SPF filters.
>
>Google apparently works similarly.  Given a valid helo and a neutral
>mfrom, the 
>spf= clause of its (ARC-)Authentication-Results: only reports the
>latter.  That 
>is to say, you need a non-RFC7208 compliant SPF filter to instruct
>DMARC.