fix: use calendarAddress/organizerCalendarAddress for scheduling, drop retired sendTo/replyTo #500

components/email/__tests__/calendar-invitation-banner.test.tsx

@@ -540,7 +540,9 @@ describe('CalendarInvitationBanner', () => {
         mocks.clientMock,
         'event-8',
         expect.objectContaining({
-          replyTo: { imip: 'mailto:organizer@example.com' },
+          // The stored event lacks an ORGANIZER, so the RSVP repair writes
+          // organizerCalendarAddress (replyTo is retired in jscalendarbis).
+          organizerCalendarAddress: 'mailto:organizer@example.com',
           participants: expect.objectContaining({
             attendee: expect.objectContaining({
               participationStatus: 'accepted',

components/email/calendar-invitation-banner.tsx

@@ -582,7 +582,12 @@ export function CalendarInvitationBanner({ email }: CalendarInvitationBannerProp
         } else {
           await updateEvent(client, eventForRsvp.id, {
             participants: repairedParticipants,
-            replyTo: replyToForRsvp ?? undefined,
+            // Stalwart routes the iTIP REPLY via the stored ORGANIZER
+            // (organizerCalendarAddress; the RFC 8984 replyTo is retired).
+            // Only repair a missing organizer - attendees may not modify it.
+            ...(replyToForRsvp?.imip && !eventForRsvp.organizerCalendarAddress
+              ? { organizerCalendarAddress: replyToForRsvp.imip }
+              : {}),
           }, true);
           setRsvpStatus(status);
           setActionNotice(t('rsvp_sent'));