The recordset depends on the OrderID being passed through the url in order to filter properly. That is the issue. If you get the OrderID into the URL then the Recordset will be filtered properly and the email will send to the user from the Recordset as you expect.
Do you have a URL where I can view the problem? It looks like the QueryString should be passed through the form action properly, so I'm not sure why it isn't appearing after the submit.