Dave Crocker writes:

> As always, I'm seeking to have thinking and discussion focus 
> on software behavior, not user behavior.
> 
> Any discussion of end user perception or behavior is distracting to
> meaningful analysis or development of technologies like DMARC.

I can't entirely agree, though I'm not without sympathy to your
point of view.  DMARC is obviously intended to be applied by
the software, and it's tempting to think that the message is
either accepted or rejected, end of story, so this shouldn't
affect the user interface or user behaviour.  In practice I
don't think it's that simple.


Of course, because of the way DMARC is applied (in the DNS)
and messages are signed (by the ISP), the sending user is
not of concern here.  The expressed concerns center on the
perceptions and behaviour of the receiving user.

If p=none (or if DMARC is not used), then the receiving
user gets the message (modulo other de-spamming techniques),
but nothing can be implied about its authenticity, so nothing
changes with respect to the non-DMARC behaviour (of the software
or the user!).

And if the message is rejected due to p=reject, then the user
never gets the message at all, so we needn't be concerned with
the receiving user's behaviour.

But if the message is delivered, either because it passes DMARC,
or it fails but is "quarantined", then the receiver will see the
message, and will make assumptions regarding the authenticity of
its origin based, most likely, on the "From:" header.  It seems
not unreasonable to suppose that the writer of a user interface
would want to indicate somehow to the user that the message was
(or was not) vetted as coming from where it says it came from.
The DMARC results seem like an obvious source of information
for such an indication.

One could argue, I suppose, that once again we're talking
about the behaviour of software, but the point of all this,
unless I woefully misunderstand, is to protect the user from
fraud due to the faked provenance of a message.  I don't think
it will ever be the case that we can sort 100% of messages as
"authentic" or "fake" before they reach the user; we have to
accept that even if we block the "known fakes" based on DMARC,
there will still be authenticated and not-checkable messages
that reach the user - and ideally we'd have a way to indicate
which are which.



Anne.
-- 
Ms. Anne Bennett, Senior Sysadmin, ENCS, Concordia University, Montreal H3G 1M8
[email protected]                                    +1 514 848-2424 x2285

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