If you want to delete an appointment, best do this via web interface in Firefox.
- If you really want to delete appointments in Thunderbird, you have to:
- Open the event
Choose: Option > Status > Canceled > Save and close.
Delete the event with: right mouse click > delete.
- If you delete the appointment without prior canceling, the appointment will be deleted in Thunderbird, but not in Zimbra.
- Calendar gets out of sync:
- From time to time it happens that Thunderbird/Lightning don't show any new appointments or changes.
- Delete the calendar in Thunderbird (you only delete the connection, not the calendar itself).
- reconnect the calendar.
- Reminder
If you create a new appointment in Tunderbird, the default is not to remind you.
If you create a new appointment in the Zimbra webinterface, the default is to remind you - take care about many unwanted reminders which will appear in Thunderbird suddenly!!!