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

Viktor Dukhovni <ietf-dane@dukhovni.org> Wed, 13 March 2019 21:49 UTC

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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Date: Wed, 13 Mar 2019 17:49:07 -0400
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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 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):

	# Mandatory PKIX authenticated TLS with back office settlement business partner,
	# And mutually agreed set of CAs.
	#
	partner.example		secure tafile=partner-cas.pem match=mx.partner.example

	# Mandatory DANE-TLS with another business partner known to support DANE
	#
	partner2.example	dane-only

	# Opportunistic DANE TLS when available with general-purpose email
	# (In real life the global default would be specified elsewhere)
	*			dane

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.

Is that right?

-- 
-- 
	Viktor.

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