title: EWS subscriptions "falling off"
body: <p>I'm working on a synchronization system, which synchronizes Outlook with another system.</p>
  
  <p>I am subscribing to around 600 mailbox calendars in an Exchange 2013 server.</p>
  
  <p>When the subscription is done, I pull the users entire mailboxes, to perform a full synchronization with the other system. This works well.</p>
  
  <p><strong>Now the problem:</strong>
  A large portion of the 600 mailboxes are not delivering push notifications to the system, when changes are made to their calendar.</p>
  
  <p>Have any of you run into similar problems, or got any idea to why this is happening?</p>
  
  <p>Is it possible to monitor something on the Exchange server, that can tell me something about the subscriptions?</p>
  
  <p>Any help is appreciated.</p>