Re: [Uta] Eric Rescorla's Discuss on draft-ietf-uta-smtp-require-tls-07: (with DISCUSS and COMMENT)

Nico Williams <nico@cryptonector.com> Thu, 14 March 2019 16:58 UTC

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Date: Thu, 14 Mar 2019 11:58:35 -0500
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From: Nico Williams <nico@cryptonector.com>
To: Eric Rescorla <ekr@rtfm.com>
Cc: uta@ietf.org, uta-chairs@ietf.org, draft-ietf-uta-smtp-require-tls@ietf.org, The IESG <iesg@ietf.org>
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Subject: Re: [Uta] Eric Rescorla's Discuss on draft-ietf-uta-smtp-require-tls-07: (with DISCUSS and COMMENT)
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On Wed, Mar 13, 2019 at 02:55:02PM -0700, Eric Rescorla wrote:
> On Wed, Mar 13, 2019 at 2:49 PM Viktor Dukhovni <ietf-dane@dukhovni.org>
> wrote:
> > > On Mar 13, 2019, at 5:13 PM, Eric Rescorla <ekr@rtfm.com> wrote:
> > >
> > > Well, I think this field should only override the outgoing and not
> > incoming policies (or be removed).
> >
> > To be clear, let's imagine a company (say a bank) with the following TLS
> > policies (written roughly Postfix-style, but should be clear even to the
> > uninitiated):
> >
> >         [...]
> >
> > I think you're saying that the company could allow its users to bypass
> > the locally-policy business partner domain rules, but must refuse to
> > allow users to exempt casual correspondence from DANE (or MTA-STS)
> > policy when published by the destination domain.

So:

  "I MAY      allow MY users to trump MY      policy"
  "I MUST NOT allow MY users to trump OTHERS' policy"

?

If my contractual relationship with my partners required me to enforce
their policies, I couldn't object to enforcing their rules.

If I don't have a contractual relationship with some domain, why should
I be required to enforce THEIR policy?  As you've pointed out, I could
just publish my email to them in a newspaper ad.

Nico
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