I’m working on an application that handles streaming notifications from Exchange Web Services and makes database updates based on those notifications. I’m monitoring a few calendar folders and tracking changes to the appointments as well as to the attendees. This all works just fine except for one piece.
When someone accepts a meeting request, that acceptance is sent via email. However, the calendar item is only updated after the user opens the email in Outlook, which presumably causes some behind-the-scenes sync to occur. If the user does not open the “accepted” or “declined” email, the appointment does not get updated. This holds true whether I am accessing the appointment via Outlook or via EWS. Simply marking the email as read via EWS doesn’t trigger the sync. Does anyone know a way to make that sync between the inbox and the calendar happen via EWS without the user having to touch Outlook?
In this case, the issue turned out to be that the Exchange mailbox itself was not set up to automatically acknowledge responses to meeting requests. There is a mailbox level setting in Exchange that controls this behavior. If it’s not set, then there is no way through EWS to force Exchange to acknowledge the response.