References for IDNs and EAI

Mail and DNS standards are published by the Internet Engineering Task Force in its RFC document series. Here are some of the more important RFCs. For a longer list see UASG 006

For SMTP

  • RFC 5321 – Simple Mail Transfer protocol, from one MTA to another (previously RFCs 821 and 2821)
  • RFC 6609 – Mail submission, from MUA to MSA (previously RFCs 2476 and 4409)

For mail message formats

  • RFC 5322 – Internet Message Format (previously RFCs 822 and 2822)
  • RFC 2045 = Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies
  • RFC 2046 – Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types
  • RFC 2047 – MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text
  • RFC 2048 – Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures
  • RFC 2049 – Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples
  • RFC 3464 – An Extensible Message Format for Delivery Status Notifications
  • RFC 6854 – Update to Internet Message Format to Allow Group Syntax in the “From:” and “Sender:” Header Fields

For POP and IMAP

  • RFC 1939 – Post Office Protocol – Version 3 (POP3)
  • RFC 3501 – Internet Message Access Protocol – Version 4rev1 (IMAP4)

For IDNs

For EAI mail

  • RFC 6530 – Overview and Framework for Internationalized Email
  • RFC 6531 – SMTP Extension for Internationalized Email
  • RFC 6532 – Internationalized Email Headers
  • RFC 6533 – Internationalized Delivery Status and Disposition Notifications
  • RFC 6855 – IMAP Support for UTF8
  • RFC 6856 – Post Office Protocol Version 3 (POP3) Support for UTF-8
  • RFC 6857 – Post-Delivery Message Downgrading for Internationalized Email Messages
  • RFC 6858 – Simplified POP and IMAP Downgrading for Internationalized Email

For PRECIS and string mapping

  • RFC 8264 – PRECIS Framework: Preparation, Enforcement, and Comparison of Internationalized Strings in Application Protocols
  • RFC 8265 – Preparation, Enforcement, and Comparison of Internationalized Strings Representing Usernames and Passwords
  • RFC 8266 – Preparation, Enforcement, and Comparison of Internationalized Strings Representing Nicknames
  • RFC 7790 – Mapping Characters for Classes of the Preparation, Enforcement, and Comparison of Internationalized Strings (PRECIS)
  • RFC 6885 – Stringprep Revision and Problem Statement for the Preparation and Comparison of Internationalized Strings (PRECIS)
  • RFC 6943 – Issues in Identifier Comparison for Security Purposes

For SASL

These define the methods for logging in and authenticating for POP, IMAP, and submission, using UTF-8 usernames and passwords.

For URLs and URIs

  • RFC 3986 – Uniform Resource Identifier (URI): Generic Syntax.
  • RFC 3897 – Internationalized Resource Identifiers (IRIs)