Re: (DMARC) Why mailing lists are only sort of special

Michael Richardson <mcr+ietf@sandelman.ca> Thu, 17 April 2014 22:20 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Dave Cridland <dave@cridland.net>
Subject: Re: (DMARC) Why mailing lists are only sort of special
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References: <CE39F90A45FF0C49A1EA229FC9899B0507D45766@USCLES544.agna.amgreetings.com> <20140414214949.32126.qmail@joyce.lan> <CE39F90A45FF0C49A1EA229FC9899B0507D460CB@USCLES544.agna.amgreetings.com> <alpine.BSF.2.00.1404142150430.32657@joyce.lan> <CAL0qLwbPMm_i0fqNSGQPv=xZaiNASy=icsRNudaNJ_3PNtX3Og@mail.gmail.com> <alpine.BSF.2.00.1404151832460.38826@joyce.lan> <CAL0qLwZUptJVw85T2FjB2HRGoOvcOUHKiQXeadM0QE9BsFVM9w@mail.gmail.com> <CAKHUCzxpwS+nR9wRGOzU_83f7XabMr0pwB5x-MHrqM-28r80kw@mail.gmail.com> <CAKHUCzzw9mufrTCOBQOkRrZU6wOM21X8Y=FUEKf=qnzS9VESjA@mail.gmail.com> <alpine.BSF.2.00.1404161654430.2065@joyce.lan> <CAKHUCzwZ29TAAjJ3_w+0aaoN-L2o+CGHYaMQ=TOEqYdVn5rQHg@mail.gmail.com>
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Date: Thu, 17 Apr 2014 18:20:45 -0400
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Cc: John R Levine <johnl@taugh.com>, "ietf@ietf.org" <ietf@ietf.org>
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Dave Cridland <dave@cridland.net> wrote:
    > Right now, my MUA treats this as a message "From John R Levine <johnl@taugh.com
    >> ". This means that any policy on the message origination comes from looking
    > solely at the taugh.com domain. We'll pretend it has a DMARC policy. Herein
    > lies the Yahoo/DMARC issue, because unless your policy essentially stipulates
    > that the IETF is allowed to spoof you, we're stuck.

If, when sending to ietf@ietf.org, taugh.com knew that it was a mailing list,
then it could include, in the message, a signed delegation saying that it was
okay for *this message* for ietf.org to impersonate him.

This is a simple application of cryptographic methods.  Keynote and SPKI
(and I think SASL) define ways to do this.

--
Michael Richardson <mcr+IETF@sandelman.ca>ca>, Sandelman Software Works
 -= IPv6 IoT consulting =-