SML

Summary

The SML working group met at IETF 125 to discuss the progress of its active drafts and a new proposal regarding machine-readable quoted content in email. Due to recent illnesses, the agenda was condensed. The primary focus was a presentation on structured quoted content, intended to solve issues related to presentation-tied quoting, localization, and nested threading. The chairs also noted that draft-ietf-sml-trust had been updated to resolve previous comments, with no further objections raised.

Key Discussion Points

Working Group Status

draft-ietf-sml-trust-01: Arnt Gulbrandsen (Chair) noted that the document was updated to reflect decisions from the previous meeting. No further comments were received on the mailing list, suggesting the document is in a stable state.
draft-ietf-sml-structured-email: This document was referenced throughout the meeting as the foundational specification for the group's work.

Structured Quoted Content

Phillip Hallam-Baker presented a proposal for a new document regarding machine-readable quoting in email.

Problem Statement: Currently, quoted content is tied to presentation (sender-controlled). This leads to issues with localized attribution lines (e.g., "On [date], [Name] wrote"), inconsistent formatting across clients (Outlook vs. Gmail), and difficulty tracking long or deeply nested inline replies.
Proposed Solution: Define structured objects (JSON-LD) to represent the quoted content independently of its visual representation. This includes objects for email messages, quoted content blocks, header blocks, and attributions.
Benefits: Allows the receiving Mail User Agent (MUA) to re-render quotes in its own native style and language, improving accessibility and UI consistency.
Technical Open Questions:
- Plain Text: Whether structured quoting is necessary for plain-text-only clients or if it should be handled in the base document (draft-ietf-sml-structured-email).
- Back-referencing: The ability to point back to the specific section of the original message being quoted to enable better UI (e.g., deep linking or inlining replies).
- JSON-LD Placement: Discussion on whether the JSON-LD should be a separate MIME part or embedded within HTML.
- Attachments: How to represent attachments that are referenced or included within a quoted section.

Discussion and Feedback

Hans-Jörg Happel suggested that identifying specific quoted chunks (back-referencing) would be valuable. He also noted that structured email signatures (already in the core draft) and @mentions are related concepts that might benefit from this work.
Arnt Gulbrandsen questioned the complexity regarding attachments, noting that most replies involving attachments already use CID (Content-ID) links.
Alexey Melnikov pointed out that some clients explicitly list attachment names in the quoted text, which could be a use case for structured representation.
Unidentified Participant inquired about backwards compatibility for clients that only understand plain text. Phillip Hallam-Baker clarified that the goal is to maintain current rendering for legacy clients while allowing modern MUAs to "upgrade" the display.
Alexey Melnikov emphasized that the placement of JSON-LD (embedded vs. separate part) should remain consistent with the core specification, draft-ietf-sml-structured-email, to ensure interoperability and to avoid confusing legacy clients.

Decisions and Action Items

A show of hands in the room and via Meetecho indicated significant interest (approximately 6-7 participants) in pursuing work on structured quoted content.
Action Item: Phillip Hallam-Baker to produce a new revision of the proposal including concrete JSON-LD examples of single and nested replies.

Next Steps

Once the updated draft with examples is posted, the chairs will initiate a formal adoption call for the structured quoted content document on the mailing list.
The group will continue to monitor the mailing list for any final comments on draft-ietf-sml-trust.

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