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Re: [dmarc-ietf] AND vs. OR (was Re: wiki vs. list?)

Douglas Otis <doug.mtview@gmail.com> Mon, 27 October 2014 21:17 UTC

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From: Douglas Otis <doug.mtview@gmail.com>
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Date: Mon, 27 Oct 2014 14:17:27 -0700
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References: <CABuGu1qDAaF0es0ikVk2KbgQaPTFeybKDu-hP=jY17txSuJxaw@mail.gmail.com> <544A41D4.2000206@isdg.net> <544A60AB.3020308@meetinghouse.net> <CABDkrv0jiDuLCVNzH5bfwYp3inn-wcRz+mPogPoRuxz0sYTU5Q@mail.gmail.com> <EED02883-386B-403E-80A5-73C17C2E45E3@gmail.com> <19409258-9DAE-49CF-BD37-DDD648BAFBED@gmail.com>
To: Brett McDowell <brettmcdowell@gmail.com>
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Archived-At: http://mailarchive.ietf.org/arch/msg/dmarc/IYsrzIlFXulYa3MzIgimlxMZZio
Cc: dmarc <dmarc@ietf.org>, Douglas Otis <doug.mtview@gmail.com>, Mike Jones <mjones@mail.agari.com>
Subject: Re: [dmarc-ietf] AND vs. OR (was Re: wiki vs. list?)
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On Oct 27, 2014, at 1:55 PM, Brett McDowell <brettmcdowell@gmail.com> wrote:

> Doug, you missed (at least) one option which I will characterize as “transient trust”.  I suggest transient trust could be implemented at scale (for many use cases) via something like OAR [1] and a companion BCP.
> 
> -Brett
> 
> [1] http://tools.ietf.org/html/draft-kucherawy-original-authres-00

Dear Brett,

Original-Authentication-Results Header Field should fall under option 4 which is trivially spoofed.  OAR represent a new (invisible) header not signed by the DMARC domain.  Such information can not safely be trusted unless authorized by DMARC domain, i.e. TPA-Labels which falls under option 1.  TPA-Label has provisions covering OAR requirements among other elements.

Regards,
Douglas Otis



>> On Oct 27, 2014, at 2:56 PM, Douglas Otis <doug.mtview@gmail.com> wrote:
>> 
>> 
>> On Oct 27, 2014, at 10:30 AM, Mike Jones <mjones@mail.agari.com> wrote:
>> 
>>> On Fri, Oct 24, 2014 at 7:22 AM, Miles Fidelman <mfidelman@meetinghouse.net> wrote:
>>> Hector Santos wrote:
>>> Hi Kurt,
>>> 
>>> If we are going to be picky about logic, then lets consider the symbolic correctness with short circuiting optimization, and it would be:
>>> 
>>>    DMARC = SPF or DKIM
>>> 
>>> <snip>
>>> 
>>> Am I missing something here?  As I understand it, DMARC is MORE than SPF and DKIM.  Specifically, as I understand it,  sender field alignment, that's bit all of us who run mailing lists, is specific to DMARC.
>>> 
>>> You're not missing anything.  
>>> 
>>> aligned SPF pass OR aligned DKIM pass = DMARC pass
>> 
>> Dear Mike,
>> 
>> Agreed.  To further clarify the obvious, the WG needs to deal with large ISPs asserting DMARC p=reject against normal user accounts where, for legitimate messages, the From header field offered by various third-party services can not be aligned with either SPF or DKIM.
>> 
>> Possible mitigations: 
>> 
>> 1) Develop a scheme for the DMARC domain to assert domain specific policy exceptions in the case of legitimate third-party services.
>> 
>> 2) Create a group syntax able to bypass DMARC p= policy assertions by offering visual indications in the From header field that an exception may have been made.
>> 
>> 3) Munge the domain of the From header field and expect users to hand edit addresses.
>> 
>> 4) Adopt a new generic method (not list specific) conditionally replacing the role of the From header field with a new (invisible) header field.
>> 
>> IMHO, options 3 and 4 should be avoided. 
>> 
>> Regards,
>> Douglas Otis
>> 
>> 
>> 
>> _______________________________________________
>> dmarc mailing list
>> dmarc@ietf.org
>> https://www.ietf.org/mailman/listinfo/dmarc
>

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