Similar question: Where are the UserProperty?

In outlook add-in FormRegion1_FormRegionShowingMethod, I write code:

mailItem = ((Microsoft.Office.Tools.Outlook.FormRegionControl)sender).OutlookItem as Outlook.MailItem;

mailItem.UserProperties.Add(USERLEVEL, Outlook.OlUserPropertyType.olText, Type.Missing, Type.Missing);

I want in RoutingAgent class get the UserProperties (USERLEVEL), Have any good suggestions and comments. Thanks!