on the registration page, find the following line:
$RecipientEmail = "".((isset($_POST["UserEmail"]))?$_POST["UserEmail"]:"") ."";include("../webassist/email/WAUE_users_Registration_1.php");
and comment it out:
//$RecipientEmail = "".((isset($_POST["UserEmail"]))?$_POST["UserEmail"]:"") ."";include("../webassist/email/WAUE_users_Registration_1.php");