Which vocabularies to use for structured data in email

[hhappel]

Current vendors and tools use a handful of concepts from the schema.org vocabulary (see also https://structured.email/content/related_work/frameworks/schema_org_for_email.html)

Options:

A) Allow for selected concepts only

• Very restrictive

B) Allow for full set of Schema.org concepts

• Still very restrictive

C) Allow for certain (e.g., IANA-registered) vocabularies

• Still somehow restrictive

D) Allow for any vocabulary; probably recommend core vocabularies such as Schema.org

• Full freedom of expression
• Might hinder interoperability (however, this is also true for MIME attachments?)