function submitform() {
  	if  (document.sub_form.email_addr.value=='')
			alert("Dit email adres is niet geldig");
			else {
  				if ( ((document.sub_form.email_addr.value.indexOf('@',1))==-1)||(document.sub_form.email_addr.value.indexOf('.',1))==-1 )
  					alert("Dit email adres is niet geldig");

  				else {
	                                        window.open("", "formPopup", "toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=0,resizable=0,height=200,width=500,toolbar=no", true);
                                 	document.sub_form.target='formPopup';
  					document.sub_form.submit();
                                   }
 		}
  }