https://learn.microsoft.com/en-us/dotnet/api/microsoft.exchange.webservices.data.exchangeservice.subscribetostreamingnotifications?view=exchange-ews-api&redirectedfrom=MSDN
ExchangeService.SubscribeToStreamingNotifications Method (Microsoft.Exchange.WebServices.Data) |...
Subscribes to streaming notifications. Calling this method results in a call to Exchange Web Services (EWS).
microsoft exchangemethodwebservicesdata