🐛(selfcheck) fix warning from a race condition in thread deletion

src/backend/core/mda/inbound.py

@@ -139,7 +139,7 @@ def deliver_inbound_message(
             channel=channel,
         )
         logger.info(
-            "Queued inbound message %s for spam processing (recipient: %s)",
+            "Queued inbound message %s (recipient: %s)",
             inbound_message.id,
             recipient_email,
         )

src/backend/core/mda/selfcheck.py

@@ -321,6 +321,10 @@ that the mail delivery pipeline is working correctly.</p>
         logger.error("Selfcheck failed: %s", e, exc_info=True)
 
     finally:
+        # Wait a bit for indexation, thread.update_stats() to be done in order
+        # to avoid race conditions on deleted objects.
+        time.sleep(5)
+
         if message:
             _cleanup_test_data(message)
         if received_message: