Produce an iCal appointment and subsequent updates via email but don't offer accept/decline options
问题 We are writing a system that has a booking feature, and we are planning to have it send *.ics files via email to attendees so they can easily add appointments to their calendars. The types of events are things like training courses (e.g. 3pm in the boardroom). We've got this working to the point that the system sends the *.ics, and using Gmail and Outlook, the user can accept the appointment which, is then added to their calendar. Sometimes an event changes (e.g. a course is cancelled or