Create a button - not a submit button.
On the click event here's the code that did it for me:
var email = xfa.resolveNode("ApprovereMail").rawValue + ";"+xfa.resolveNode("AdmineMail").rawValue;
var subject = "Your subject goes here;
var body = "Your body goes here";
event.target.submitForm({cURL:"mailto: "+ email +"?subject=" + subject +"&body=" + body,cSubmitAs:"PDF",cCharset:"utf-8"});