It's been discussed already here on stackoverflow ( Appointment.Save and Appointment.Update always set IsMeeting to true ) that EWS has limitations on how meeting invitations can't be sent automatically when creating new calendar items / meetings inside a public folder.
Since I really need to send the meeting to the calendars of the various attendees I was wondering if anybody has ever discovered a workaround for this strange behavior (I can't even find a way to send meeting invitations programmatically).
The only thing that seems to be working is to forward the calendar item to the address of the attendees, but that's really not an option since it only makes the meeting available as an attachment in the email.
on msdn they have a sample that create and sends the invite
but this will not work for public folders:
"The reason it shouldn't work is because public folders don't publish free/busy information. You cannot invite a public folder to a meeting nor can you see if a public folder is available."