fix: ignore all RCPT TO: parameters

Stalwart sends `NOTIFY=DELAY,FAILURE`
to request Delivery Status Notifications.
aiosmtpd does not support any parameters,
not just ORCPT, so we have to ignore all of them.

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ## untagged
 
+- Ignore all RCPT TO: parameters
+  ([#651](https://github.com/chatmail/relay/pull/651))
+
 - Use max username length in newemail.py, not min
   ([#648](https://github.com/chatmail/relay/pull/648))
 

chatmaild/src/chatmaild/filtermail.py

@@ -197,11 +197,13 @@ class HackedController(Controller):
 
 class SMTPDiscardRCPTO_options(SMTP):
     def _getparams(self, params):
-        # aiosmtpd's SMTP daemon fails to handle a request if there are RCPT TO options
+        # Ignore RCPT TO parameters.
-        # We just ignore them for our incoming filtermail purposes
+        #
-        if len(params) == 1 and params[0].startswith("ORCPT"):
+        # Otherwise parameters such as `ORCPT=...`
-            return {}
+        # or `NOTIFY=DELAY,FAILURE` (generated by Stalwart)
-        return super()._getparams(params)
+        # make aiosmtpd reject the message here:
+        # <https://github.com/aio-libs/aiosmtpd/blob/98f578389ae86e5345cc343fa4e5a17b21d9c96d/aiosmtpd/smtp.py#L1379-L1384>
+        return {}
 
 
 class OutgoingBeforeQueueHandler: