Re: [dmarc-ietf] New version of draft-ietf-dmarc-arc-usage posted

"John Levine" <johnl@taugh.com> Sat, 27 October 2018 21:54 UTC

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Subject: Re: [dmarc-ietf] New version of draft-ietf-dmarc-arc-usage posted
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In article <ee344a3b-cb31-d552-6c88-05cf4ad6146f@wizmail.org>,
Jeremy Harris  <jgh@wizmail.org> wrote:
>> New version: https://tools.ietf.org/html/draft-ietf-dmarc-arc-usage-06
>
>How about another subsection 5.x saying when Originating ADMDs should
>take any ARC action?  For starting a new ARC chain I assume the answer
>is normally "don't" - but perhaps there is an exception when a message
>is already DKIM-signed, or when SPF for it would be invalidated by
>forwarding (despite it being in-theory a local ADMD source)?

Seems to me that's pretty simple: you should add an ARC seal when you
do something that might break DMARC validation, which means modifying
the contents of the message (breaks DKIM) or remailing a message
(breaks SPF.)

It is my impression that if your message already has a local A-R
header, it's a good candidate for adding an ARC seal.  If not, it
probably isn't even though you could in principle add your own A-R
which only has arc=none.

R's,
John
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