Read back the provider message-id from the sent copy on the microsoftgraph route

[jbagsik]

Parent

#1

Problem

On the Microsoft Graph structured send route a sender cannot set its own RFC 5322 Message-ID — Graph builds the MIME itself and assigns its own. The transport therefore strips Message-ID before the API call, and mail_send_logs.message_id stays null on this route. The only durable identifier that survives today is the self-assigned correlation header (X-Moox-Mail-Correlation-Id). Without the provider's own message id there is no stable second key tying a sent message to its sent copy for later correlation.

What to build

After a successful send on a mailer whose transport does not stamp an on-wire Message-ID (e.g. microsoftgraph), read the provider-assigned message id back from the sent copy and store it on the log row.

• A ProviderMessageIdReader implementation that, given the sent message, obtains the provider's message id through a follow-up lookup of the sent copy, matched by the self-assigned correlation header (for Graph: the internetMessageId of the item in Sent Items).
• Bound per mailer and activated through the existing read_back_provider_id switch — off by default, on for the Graph route.
• Writes the value to mail_send_logs.message_id (the RFC 5322 id read from the sent copy) and/or provider_reference.
• A failed or absent read-back never fails the send: the row stays sent/suppressed with the id left null, as today.

Acceptance criteria

• After a successful send on the Graph route, the sent copy's message id is stored on the log row
• The sent copy is located by the self-assigned correlation header
• Read-back is switchable per mailer via read_back_provider_id, off by default
• A failed or absent read-back leaves the row successful with the id null and does not raise
• Routes that already carry an on-wire Message-ID are unaffected

Blocks

• Correlate returned reports and auto-replies to the message that caused them #10 — its matching relies on "the identifier read back from the provider's sent copy" as the primary key; that identifier is produced here.