title: Reading ALL custom properties on Exchange Server with EWS
body: <p>I would like to read all "Custom properties" from EWS-Items. I do have the names of the properties (e.g. "duration" oder "distance") but I did not create them (my clients did).</p>
  
  <p>I guess I will have to use "ExtendedProperties" of the "Item" class. But when I use Item.Bind() with a Property-set I need to know a GUID which I don't have! Microsoft says (<a href="http://msdn.microsoft.com/en-us/library/exchange/dd633697%28v=exchg.80%29.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/exchange/dd633697%28v=exchg.80%29.aspx</a>):
  "Create a GUID identifier from the GUID that was used when the extended property was created."</p>
  
  <p>I don't have these GUIDs because I did not create the properties.
  I guess the only chance is to use Item.Bind() without a specific property set. Would that slow down the process (I need to call this for every item in the mailbox)?</p>
  
  <p>I basically would like to iterate with a clause like this: 
  if (extendedProperty.PropertyDefinition.Name == "duration")</p>
  
  <p>Any ideas how to do this?</p>
  
  <p>Thanks </p>
  
  <p>Martin</p>