From: Jeremy Harris Date: Wed, 17 Apr 2024 12:36:17 +0000 (+0100) Subject: Docs: update info on MTA-STS. Bug 3091 X-Git-Tag: exim-4.98-RC0~39 X-Git-Url: https://git.exim.org/exim.git/commitdiff_plain/2159057b255a1bc6d870ebddef858ee2b47d331d Docs: update info on MTA-STS. Bug 3091 --- diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt index 8164dcd74..182e5644c 100644 --- a/doc/doc-docbook/spec.xfpt +++ b/doc/doc-docbook/spec.xfpt @@ -30542,12 +30542,17 @@ Section 4.3 of that document. .subsection General Under GnuTLS, DANE is only supported from version 3.0.0 onwards. -DANE is specified in published RFCs and decouples certificate authority trust +DANE is specified in RFC 6698. It decouples certificate authority trust selection from a "race to the bottom" of "you must trust everything for mail to get through". -There is an alternative technology called MTA-STS, which -instead publishes MX trust anchor information on an HTTPS website. At the -time this text was last updated, MTA-STS was still a draft, not yet an RFC. +It does retain the need to trust the assurances provided by the DNSSEC tree. + +There is an alternative technology called MTA-STS (RFC 8461), which +instead publishes MX trust anchor information on an HTTPS website. +The discovery of the address for that website does not (per standard) +require DNSSEC, and could be regarded as being less secure than DANE +as a result. + Exim has no support for MTA-STS as a client, but Exim mail server operators can choose to publish information describing their TLS configuration using MTA-STS to let those clients who do use that protocol derive trust