Exchange EWS ErrorCalendarIsNotOrganizer despite being the organizer

0
votes

I'm trying to cancel a meeting I created by using an EWS XML CreateItem request (against a 2013 server):

<ns2:CreateItem MessageDisposition="SendAndSaveCopy"><ns2:Items>
<ns1:CancelCalendarItem>
<ns1:ReferenceItemId Id="AAMkA...." ChangeKey="DwAAA..."/>
</ns1:CancelCalendarItem>
</ns2:Items></ns2:CreateItem>

So far so good, however Outlook denies me access with the ResponseCode "ErrorCalendarIsNotOrganizer" / "User must be an organizer for CancelCalendarItem action".

A look in the event detail by using GetItem with BaseShape=ALL_PROPERTIES reveals that the account I use is set as Organizer, however at the same time:

  • the IsOrganizer field is set to false
  • in EffectiveRights the fields Read, Modify and Delete are true.
  • I can delete the appointment lateron using a DeleteItem request and it works, however it only removes the appointment from the room's calendar but not from the mailboxes of the attendees.

What causes this? There is no impersonation in use, only the service account I use has delegation access to every room mailbox (to be able to see all appointments).

1
exchange-serverexchangewebservices

1 Answers

1
votes

I can delete the appointment lateron using a DeleteItem request and it works, however it only removes the appointment from the room's calendar but not from the mailboxes of the attendees.

It sounds like your accessing the appointment in the Room Mailboxes calendar ? this is why even if your using the account that is the organizer of that appointment the isOrganizer will return as false because this property is only true on the copy of the Appointment in the Organizers calendar. To correctly cancel the meeting you need to do that on the calendar of the Organizer (not the rooms or any attendee instance of the meeting). This will still only delete the appointment in the organizer calendar and send cancellation messages to the attendees.

An important point is that all instances of the meeting stored in the Attendees and Meeting Room calendars are separate Exchange Store items with no direct link. So deleting the organizer instance (or any attendee instance) has no affect on the other attendees instances these must be processed separately by the attendees themselves based on the cancellation message that is received.