Re: (DMARC) Why mailing lists are only sort of special (Martin Rex) Thu, 17 April 2014 13:11 UTC

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Subject: Re: (DMARC) Why mailing lists are only sort of special
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To: Yoav Nir <>
Date: Thu, 17 Apr 2014 15:11:34 +0200 (CEST)
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From: (Martin Rex)
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Yoav Nir wrote:
> On Apr 17, 2014, at 9:35 AM, Dave Cridland <> wrote:
>> Right now, my MUA treats this as a message
>> "From John R Levine <>"m>". This means that any policy
>> on the message origination comes from looking solely at the
>> 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.
> Then perhaps this is what needs to change. John R Levine did not send
> you a message. He sent a message to the list. It is the list software
> that sent you a message. So perhaps the From field should have been
> ?From: IETF Mailing list on behalf of John R Levine <>?g>?.

But that is EXACTLY what the IETF mailing list exploder *IS* doing
exactly as it has been specified for ages:

            The "From:" field specifies the author(s) of the message,
   that is, the mailbox(es) of the person(s) or system(s) responsible
   for the writing of the message.  The "Sender:" field specifies the
   mailbox of the agent responsible for the actual transmission of the

  From: Yoav Nir <>
  Subject: Re: (DMARC) Why mailing lists are only sort of special
  Sender: ietf <>
  Date: Thu, 17 Apr 2014 13:50:30 +0300
  Message-ID: <>
  To: Dave Cridland <>
  CC: "" <>

Something as old as Outlook 2003 will properly display a message
that is received with a "Sender:" as "<Sender> on behalf of <From>"