[Uta] Updated SMTP STS Draft

["Brotman, Alexander" <[e-mail]>]

Hello,

We've incorporated much of the feedback we've received from the community, and would like to present updated drafts. 

* One of the most evident changes is that we've split the draft into two separate documents; one for the STS policy, and one for the TLS reporting.  These are meant to replace the original SMTP STS draft (https://datatracker.ietf.org/doc/draft-margolis-smtp-sts-00).
* We've altered the name a bit from "SMTP STS" to "MTA STS" to be more in line with DEEP, and have also added elements for the DEEP registry.  
* After some deliberation amongst the authors, we've also decided to remove the DNSSEC-related options for the STS policy, which should simplify work for those wishing to deploy STS validation.  
* Within the TLS reporting, we've explicitly mentioned several failure modes, including those specifically relating to DANE and MTA STS.  
* We've also altered the report syntax to use JSON instead of XML.  

Please see drafts here:

https://datatracker.ietf.org/doc/draft-brotman-mta-sts/

And

https://datatracker.ietf.org/doc/draft-brotman-smtp-tlsrpt/

We'd like others to review and encourage further discussion relating to these drafts.  Thank you for your time.

--
Alex Brotman
Engineer, Anti-Abuse
Comcast