RFC 4021: Registration of Mail and MIME Header Fields

This document defines the initial IANA registration for permanent mail and MIME message header fields, per RFC 3864. [STANDARDS-TRACK]

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Incoming relationships (6 related RFCs)

Updated by, Informatively referenced by — RFC 5322: Internet Message Format
Normatively referenced by — RFC 5598: Internet Mail Architecture
Normatively referenced by — RFC 6857: Post-Delivery Message Downgrading for Internationalized Email Messages
Normatively referenced by — RFC 7193: The application/cms Media Type
Informatively referenced by — RFC 8823: Extensions to Automatic Certificate Management Environment for End-User S/MIME Certificates
Informatively referenced by — RFC 9788: Header Protection for Cryptographically Protected Email