What it is
Some mailbox providers recognize JSON-LD or microdata describing reservations, orders, confirmations, and actions associated with a message.
Why it matters
Structured data can expose useful actions in a mailbox UI, but support is provider-specific and often requires sender registration.
How to implement
Describe the same entity and action the recipient can see, use canonical HTTPS destinations, meet provider authentication requirements, and keep the normal message and website fully functional.
Common mistakes
- Marking up an action not present in the message.
- Treating provider approval as a web standard.
- Putting secrets in visible structured data.
Verification
Validate the markup, send through the provider’s approved production path, and confirm unsupported clients simply ignore it without losing function.
Sources
- Schema.org EmailMessage — Schema.org
- Email markup overview — Google