Add bounce mailbox processing

src/govoplan_mail/backend/delivery_outbox.py

@@ -5,6 +5,8 @@ import hashlib
 import json
 from collections import Counter
 from datetime import datetime, timedelta, timezone
+from email import policy
+from email.parser import BytesParser
 from typing import Any
 
 from sqlalchemy import or_, select
@@ -105,6 +107,18 @@ def _message_bytes(command: MailDeliveryCommand) -> bytes:
     return message
 
 
+def _rfc_message_id(message: bytes) -> str | None:
+    try:
+        value = BytesParser(policy=policy.default).parsebytes(
+            message,
+            headersonly=True,
+        ).get("Message-ID")
+    except Exception:
+        return None
+    normalized = " ".join(str(value or "").split())
+    return normalized[:998] or None
+
+
 def _delivery_payload(
     *,
     command_type: str,
@@ -169,6 +183,7 @@ def submit_delivery_command(
     if retention_days < 1:
         raise MailDeliveryError("Mail payload retention must be at least one day")
     digest = hashlib.sha256(message_bytes).hexdigest()
+    rfc_message_id = _rfc_message_id(message_bytes)
     request_hash = _canonical_hash(
         _delivery_payload(
             command_type=command_type,
@@ -219,6 +234,7 @@ def submit_delivery_command(
         from_header_encrypted=encrypt_secret(from_header),
         message_encrypted=encrypt_secret(base64.b64encode(message_bytes).decode("ascii")),
         message_sha256=digest,
+        rfc_message_id=rfc_message_id,
         message_size_bytes=len(message_bytes),
         recipient_count=len(clean_recipients),
         status="pending",
@@ -299,6 +315,7 @@ def delivery_command_summary(
         "failure_code": command.failure_code,
         "failure_summary": command.failure_summary,
         "message_sha256": command.message_sha256,
+        "rfc_message_id": command.rfc_message_id,
         "message_size_bytes": command.message_size_bytes,
         "created_at": command.created_at,
         "completed_at": command.completed_at,