NIST requests comments on the second draft of Special Publication (SP) 800-177, Trustworthy Email. This draft is a complimentary guide to NIST SP 800-45 Guidelines on Electronic Mail Security and covers protocol security technologies to secure email transactions. This draft guide includes recommendations for the deployment of domain-based authentication protocols for email as well as end-to-end cryptographic protection for email contents. Technologies recommended in support of core Simple Mail Transfer Protocol (SMTP) and the Domain Name System (DNS) include mechanisms for authenticating a sending domain (Sender Policy Framework (SPF), Domain Keys Identified Mail (DKIM) and Domain based Message Authentication, Reporting and Conformance (DMARC). Email content security is facilitated through encryption and authentication of message content using S/MIME and/or Transport Layer Security (TLS) with SMTP. This guide is written for the federal agency email administrator, information security specialists and network managers, but contains general recommendations for all enterprise email administrators.

The public comment period closed April 29th, 2016. 
Email comments to SP800-177@nist.gov