Re: [dmarc-ietf] Response to a claim in draft-crocker-dmarc-author-00 security considerations

[John Levine <[e-mail]>]

In article <[e-mail]> you write:
>Why should the rest of end-users suffer?  (some might say)
>
>Granted, we are a university.  Maybe these are just faculty being hyper-sensitive to how
>their messages are appearing to their peers/students.  But isn't that enough evidence that
>end-users *are* relevant?  With time, maybe we can change these end-user expectations, and
>From rewriting will be the new reality that people will accept.

I don't think the claim is that users don't see anything, it's that
they're no good at using what they see to make security decisions,
something that has more to do with mental models and metaphors between
what's on the screen and reality.

>I think that draft-kucherawy-dkim-transform-02 is getting at what I was originally thinking. 
>In my opinion, MLMs will *always* need to munge, because they will never know if an arbitrary
>receiver will trust their non-munged mail.  Giving the receivers a way to un-munge (if they
>can and/or want and/or trust) would be a productive path forward out of this situation.

We already have a couple of ways to do reversible message munging,
starting with MIME message wrapping. In principle it works fine, in
practice it's awful because MUAs don't show wrapped messages
consistently and often in ways that are painful, e.g., you can see the
original author address but there's no button you can push to respond
to it.

Unwrapping a MIME attachment is a lot easier than the proposed DKIM
unmunging but I doubt either is going to show up in MTAs any time
soon.  Perhaps you could do it in the mail gateway.

R's,
John