RFC 9979 - Registration of Further IMAP/JMAP Keywords and Mailbox Name Attributes

• Status: Informational
• Published: May 2026
• Stream: IETF
• Errata: No Errata

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Abstract

This document defines a number of keywords and mailbox name attributes that have been in use across different server and client implementations. It defines their intended use and registers them with IANA to avoid name collisions.

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Contents

• 1. Introduction
• 2. Requirements Language
• 3. Flag Color Keywords
  • 3.1. Definition of the $MailFlagBit_ Message Keywords
  • 3.2. Implementation Notes
• 4. Attachment Detection Keywords
  • 4.1. $hasattachment
  • 4.2. $hasnoattachment
• 5. Memos Keywords
  • 5.1. $hasmemo
  • 5.2. $memo
• 6. Subscription Management Keywords
  • 6.1. $canunsubscribe
  • 6.2. $unsubscribed
• 7. Other Message Keywords
• 8. Mailbox Name Attributes
• 9. IANA Considerations
• 10. Security Considerations
• 11. Normative References
• Authors' Addresses

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Related Resources

• Official Text: RFC 9979
• Official Page: RFC 9979 DataTracker
• Errata: RFC Editor Errata