If there's an incoming mail that triggers:
[txdav.caldav.datastore.scheduling.imip.inbound#warn] Mail gateway didn't find an icalendar attachment in message
[txdav.caldav.datastore.scheduling.imip.inbound#warn] Mail gateway forwarding reply back to organizer
and pop3 is used, then
this mail is forwarded every $polling_interval to the organizer, and
If there's an incoming mail that triggers: [txdav.caldav.datastore.scheduling.imip.inbound#warn] Mail gateway didn't find an icalendar attachment in message [txdav.caldav.datastore.scheduling.imip.inbound#warn] Mail gateway forwarding reply back to organizer
and pop3 is used, then
Suggested solution: Make https://github.com/apple/ccs-calendarserver/blob/b736fd0248ee42ac7a3b7d2af7fb3a55962d39ba/txdav/caldav/datastore/scheduling/imip/inbound.py#L190
a configuration setting.