[enhancement]: Add Message ID to webhook payloads and delivery events

[ljuti]

Which feature or improvement would you like to request?

I'd like to see this feature: Delivery events and webhook payloads should include messageId key/value pair so that individual messages could be identified as they move through SMTP transactions and delivery flow.

The following events should include messageId in their payload:

• delivery.* events
• queue.* events

Is your feature request related to a problem?

The problem: When operating a multi-role email server infrastructure, it's currently difficult to accurately track a message through the delivery flow. For example, if one is using an outbound SMTP gateway for accepting messages from authenticated users for delivery, and ultimately delivering the messages through a relay to recipients, there are no identifiers one could rely on to accurately track the message.

messageId is available in MTA hooks, so it's easy to register new messages entering the delivery flow, but since this property is not currently available in the event payloads in the later stages, accurate tracking is not possible.

Code of Conduct

• [X] I agree to follow this project's Code of Conduct

[mdecimus]

Two comments regarding this:

• Stalwart uses an internal queueId to track a message from acceptance to delivery, this is because the Message-ID within a message is generated by the remote server and in some (rare) cases these are duplicated or missing. The Message-Id field is included in the message-ingest.[ham|spam] event which also includes the queueId, which you can then use to obtain past events using the REST API.
• Webhook events do not include past information from the span to keep the payload compact. If you would like to obtain additional information after receiving a webhook event, you should use the REST API (or query your OpenTelemetry store) to obtain past events by either spanId or queueId.

[ljuti]

Fair enough. I'll work on finding another approach to address my use case.