title: Get all contacts from exchange server
body: <p>I want to get all users from Exchange server, I don't want to get user's contacts. In fact, I want to get all AD users as Active Directory which we can't connect to.</p>
  
  <pre><code>     mExchangeService.ImpersonatedUserId = new ImpersonatedUserId
          {
              Id = "jack@aa.com",
              IdType = ConnectingIdType.SmtpAddress
          };
          var contacts = _mExchangeService.FindItems(new FolderId(WellKnownFolderName.Contacts),new ItemView(1000)); 
  </code></pre>
  
  <p>I can above code to get user's contact, but that's not I want, I want use a service account to get all Exchange web service users.</p>