Hi
When one user create repeated event, add attendees and delete only first event, other attendees receive message with invite to this deleted event
NC-25.0.12 CalendarApp-4.5.2
May be it bug is not from calendar app. It from NC’s calDAV server, becouse I found email alerts in /apps/dav/.
UPD1: I upgraded NC upto 27.1.3 and this effect was changed:
Now, then owner delete first repeated event, other attendees receive message “updated the event”, but it was deleted.
It better, but is not correct I think.