title: Display Outlook Appointment Extended Properties in outlook
body: <p>Is it possible to display outlook appointment extended properties in a custom outlook form or maybe an outlook addin? I have set the extended properties against the appointments using EWS. An example of how I have set them is below:</p>
  
  <pre><code>private static readonly ExtendedPropertyDefinition extendedPropertyEventID = new ExtendedPropertyDefinition(
                                                                                      new Guid("{00020329-0000-0000-C000-000000000046}"),
                                                                                      "EventID",
                                                                                      MapiPropertyType.String);
  
  
  appointment.SetExtendedProperty(extendedPropertyEventID, "123456");
  </code></pre>