title: Accessing room calendar in EWS returns "No mailbox with such guid"
body: <p>I am trying to get the list of meetings from a room shared calendar using Microsoft Exchange (EWS) API and it's returning this error: <strong>No mailbox with such guid</strong></p>
  
  <pre><code>var service = new ExchangeService();
  service.Credentials = new NetworkCredential("username", "password");
  service.Url = new Uri("exchangeUrl");
  
  var startDate = DateTime.Today;
  var endDate = DateTime.Today.AddDays(1);
  var cv = new CalendarView(startDate, endDate);
  var mailboxToAccess = "room_email_address@mycompany.com";
  var calendarFolderId = new FolderId(WellKnownFolderName.Calendar, mailboxToAccess);
  var appointments = service.FindAppointments(calendarFolderId, cv); // &lt;&lt; Exception happens here
  </code></pre>
  
  <p>Any ideas what could be wrong?</p>