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

John R Levine <johnl@taugh.com> Thu, 04 February 2021 16:43 UTC

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Date: 4 Feb 2021 11:43:06 -0500
Message-ID: <b9c3487-44ed-a132-d42-47364fd819b4@taugh.com>
From: "John R Levine" <johnl@taugh.com>
To: "Alessandro Vesely" <vesely@tana.it>, dmarc@ietf.org
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Subject: Re: [dmarc-ietf] Ticket #1 - SPF alignment
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I really do not see anything to change here, and we have a lot of other 
tickets to work on.  Please, can we stop and close this one?


> On Wed 03/Feb/2021 19:12:26 +0100 John Levine wrote:
>> In article <b396cf21-05f4-a1a4-5abc-78c5aa276473@tana.it> you write:
>>> On Tue 02/Feb/2021 20:13:42 +0100 John R Levine wrote:
>>>> It's existing practice and I see no reason to change it.
>>> 
>>> Software changes all the time.  If we change, ...
>> 
>> Urrgh. There are still MTAs that haven't been updated from RFC 821. If
>> you want a real standard, the closer you can make it to what the
>> running code does, the most likely it will work.
>
>
> How about this:
>
>    NOTE: Historically, SPF was focused on the mfrom identifier.  The helo
>    identifier was retrofitted later, in order to account for delivery status
>    notifications.  Earlier DMARC specifications followed suit. 
> Subsequently,
>    it turned out that SPF records for the helo identifier are actually 
> sharper
>    than those for mfrom, thereby making successful helo verifications very
>    reliable.  However, in the vast majority of cases the mfrom identifier is
>    aligned with the main DMARC identifier, while the helo identifier often
>    does not have a corresponding SPF record.  Therefore, the common practice
>    of using just the SPF result of mfrom unless empty is still a valid
>    heuristic.
>
> ?
>
>
> Best
> Ale
>

Regards,
John Levine, johnl@taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly