Hi 
I am using the following code to fetch Messages: 
List AllEnvelopes = new List(); 
TotalCount = 0; 
using (var client = GetGraphClient(apiUrl, settings, mailbox)) 
{ 
var inbox = client.ListFolders().First(fi => fi.D…...NullReferenceExcepti: Object reference not set to an instance of an object. Can...a property or method on an object that is null. Here are some...