diff --git a/wallace/module_resources.py.ORIG b/wallace/module_resources.py
--- a/wallace/module_resources.py.ORIG
+++ b/wallace/module_resources.py
@@ -323,7 +323,7 @@
             continue
 
         # ignore updates and cancellations to resource collections who already delegated the event
-        if len(receiving_attendee.get_delegated_to()) > 0 or receiving_attendee.get_role() == kolabformat.NonParticipant:
+        if len(receiving_attendee.get_delegated_to()) > 0 or (receiving_attendee.get_role() == kolabformat.NonParticipant and not receiving_attendee.get_rsvp()):
             done = True
             log.debug(_("Recipient %r is non-participant, ignoring message") % (receiving_resource['mail']), level=8)