Custom Entity Properties

 I have an Entity called EmailFolder.  In code, I add an int property called NewEmailCount.  I then link it to the SL project so it is accessible on both the client and server.  I then pass an instance of the entity from SL up to the Server via an  InvokeServerMethod, do some stuff, set the property and pass it back to the client. 
The issue is that the NewEmailCount is always zero when it gets back to the client.  Is this correct?  It seems to me that it would be serialized and sent back over the wire to the client with the value intact.  But perhaps unless it part of the actual entity, it is just discarded and resets to the default value once it gets back to the client.

The reason the property is not back by a database element is that I don't really need to save the property.