Merge pull request 'Return Permanent Failure when dealing with undeliverable mail' (#162) from perm-fail-on-unencrypted into develop

Reviewed-on: #162

lacre/daemon.py

@@ -71,13 +71,17 @@ class MailEncryptionProxy:
                 else:
                     LOG.exception('Unexpected exception caught, bouncing message')
 
-                return xport.RESULT_TRANS_FAIL
+                return xport.RESULT_PERM_FAIL
 
         return xport.RESULT_OK
 
     def _send_unencrypted(self, operation, envelope: Envelope, send: xport.SendFrom):
         # Do not parse and re-generate the message, just send it as it is.
-        send(envelope.original_content, operation.recipients())
+        try:
+            send(envelope.original_content, operation.recipients())
+        except:
+            LOG.exception('Unencrypted delivery failed, returning PERMANENT FAILURE to sender')
+            raise xport.PermanentFailure()
 
     def _beginning(self, e: Envelope) -> bytes:
         double_eol_pos = e.original_content.find(DOUBLE_EOL_BYTES)