Cancellations: Call It Off in the Thread and the Calendar Clears

Reply to the thread saying the meeting is off and Sarra marks it cancelled, deletes the event from the host's connected calendar, and tells the other side in the same thread. She suppresses the calendar provider's own automated cancellation notice and sends a plain message instead, so nobody receives two conflicting emails about the same meeting.

Cancel by reply; the calendar event is removed and everyone is told.

Reply to the meeting thread saying it needs to be cancelled.

Sarra classifies the message as a cancellation, with guards for phrasing like "don't cancel" so she does not act on a negation.

The meeting is marked cancelled in Sarra so no further follow-ups are sent for it.

The calendar event is deleted from whichever provider it was created on.

A short, clearly worded cancellation message goes out on the thread.