Re: DMARC from the perspective of the listadmin of a bunch of SMALL community lists

Dave Crocker <dhc@dcrocker.net> Sun, 20 April 2014 20:44 UTC

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Date: Sun, 20 Apr 2014 13:41:43 -0700
From: Dave Crocker <dhc@dcrocker.net>
Organization: Brandenburg InternetWorking
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To: ned+ietf@mauve.mrochek.com, "Murray S. Kucherawy" <superuser@gmail.com>
Subject: Re: DMARC from the perspective of the listadmin of a bunch of SMALL community lists
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reference quibble...



On 4/16/2014 11:00 PM, ned+ietf@mauve.mrochek.com wrote:
>> On Sat, Apr 12, 2014 at 4:35 PM, <ned+ietf@mauve.mrochek.com> wrote:
>>> The underlying technical issue is that the two technologies DMARC is built
>>> on -
>>> DKIM and SPF - both attach additional/restrictive semantics to
>>> longstanding mail
>>> system fields. (Broadly speaking, From: for DKIM and MAIL FROM for SPF.)
>
>> Something's amiss here.  What new semantics does DKIM attach to From:?  As
>> far as I know, it only requires that the field be signed.  It doesn't
>> require that it be interpreted in a particular way or that it contain any
>> particular value.
>
> I was trying to be brief. Yes, I'm well aware that DKIM can be used in other
> ways. This entire discussion is within the context of DMARC here. Do you
> disagree that DMARC's use of DKIM and SPF assign additional semantics to header
> and envelope from fields respectively?


Not really.  In fact, I fear that that's a bit like saying that TCP 
makes IP a reliable, byte-sequenced protocol...

Rather, DMARC defines its /own, additional/ meaning, but it does not 
change DKIM or SPF.  They do what they've been doing for quite awhile. 
DMARC does something /more/.

Essentially, DMARC takes the domain name used in DKIM d= and/or SPF 
"protected" rfc2321.MailFrom and invents a new requirement, namely that 
that domain name be the one used in the author's rfc2822.From field's 
addr-spec's <domain>.



d/

-- 
Dave Crocker
Brandenburg InternetWorking
bbiw.net