The ResponseRequested property indicates whether a response is requested for this appointment. Read/write.
objAppointment.ResponseRequested
Boolean
The ResponseRequested property contains True if the messaging user that created a MeetingItem object from this appointment wishes a response. It contains False if there is no request for a response. ResponseRequested defaults to True.
Changes you make to properties on an AppointmentItem object take effect when you call the Send or Update method.