On 4/28/15 6:44 AM, Dave Crocker wrote:
> On 4/25/2015 8:34 AM, Stephen J. Turnbull wrote:
>> Of course, the reality that this is an IETF WG, and what we can
>> do that has effect with high probability is change wire protocols.
>> MUA presentation is outside of our bailiwick,
> Exactly.
>
> Which means that an extended thread discussing user behavior is a
> distraction from the working group's focus, especially absent careful,
> and objective documentation of UCD/UX-related efficacy experiments.

Dear Dave,

One of the early versions of DMARC included considerations
related to the delivery of messages that fall into the
category of "reject".
,--
Mail Receivers MAY choose to accept email that fails the
DMARC mechanism check even if the Domain Owner has published
a "reject" policy. Mail Receivers SHOULD make a best effort
not to increase the likelihood of phishing if it chooses not
to reject, against policy.
'--

One of the later versions of DMARC cautioned about applying
DMARC policy against user email.  It seems DMARC now expects
to transform SMTP where the identity of the author becomes
less deterministic by being the only identity considered.
The various transformation schemes afford less security by
allowing more ways to obscure the true source of a message
when all that is seen is the From.

When a few domains decide to publish "reject" policies
disruptive for valid and legitimate mediated services do so
by ignoring the role assigned the From and that of the
Sender.  It should not matter how the identity responsible
for actually sending the message is displayed.  It should be
validated where possible and enter into considerations about
whether the message should be rejected and even that the
actual sender be conveyed to recipients when it is not.

At least early on, some recognized a need to mitigate such
disruption where of course, a best effort should not
increase the likelihood of phishing where the actual sender
identity be confirmed.  Something that DMARC currently fails
to provide.  In addition, moving valid messages into
Quarantine folders causes an increasing number of users
dangerously wading through this folder as well.  In this
respect, DMARC is making the problem worse and not better
when DMARC policy abuses valid and legitimate messages by
ignoring the valid role of the Sender for non-transactional
email exchanges.

Regards,
Douglas Otis

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