fix: signal rejected IPR response emails (#7584)

ietf/ipr/tests.py

@@ -789,7 +789,9 @@ Subject: test
         
         mock_process_response_email.side_effect = None
         mock_process_response_email.return_value = None  # rejected message
-        ingest_response_email(message)  # should _not_ send an exception email on a clean rejection
+        with self.assertRaises(EmailIngestionError) as context:
+            ingest_response_email(message)
+        self.assertIsNone(context.exception.as_emailmessage())  # should not send an email on a clean rejection
         self.assertTrue(mock_process_response_email.called)
         self.assertEqual(mock_process_response_email.call_args, mock.call(message))
         mock_process_response_email.reset_mock()

ietf/ipr/utils.py

@@ -92,8 +92,10 @@ def generate_draft_recursive_txt():
 def ingest_response_email(message: bytes):
     from ietf.api.views import EmailIngestionError  # avoid circular import
     try:
-        process_response_email(message)
+        result = process_response_email(message)
     except Exception as err:
+        # Message was rejected due to an unhandled exception. This is likely something
+        # the admins need to address, so send them a copy of the email.
         raise EmailIngestionError(
             "Datatracker IPR email ingestion error",
             email_body=dedent("""\
@@ -104,3 +106,8 @@ def ingest_response_email(message: bytes):
             email_original_message=message,
             email_attach_traceback=True,
         ) from err
+
+    if result is None:
+        # Message was rejected due to some problem the sender can fix, so bounce but don't send
+        # an email to the admins
+        raise EmailIngestionError("IPR response rejected", email_body=None)