LiveCycle's purpose-built submit buttons don't allow programming so I've made my own data submission button.
Here's the code on the button's click event:
var email = ************;
So it functions as I want it to except that it uses a default subject of the xml file name. It's going to an email address, not a server, so for the purpose of possible debugging, I'd like to be able to have a dynamic subject field. Using the event.target.mailForm function, you can use the parameter cSubject.