We are developing a long time running windows service which is monitoring an email account with EWS API 2.2. The connection interval is the maximum allowed value 30 minutes, and thus the connection is reopened inside the OnDisconnect event handler every 30 minutes. After the service keeps on running for couple of days (1 day or 2 or more), the error happens:
You must add at least one subscription to this connection before it can be opened.:You must add at least one subscription to this connection before it can be opened.
StackTrace: ' at the method of Void OnDisconnect(System.Object, Microsoft.Exchange.WebServices.Data.SubscriptionErrorEventArgs).
Any idea?