It looks like this would work.
Try adding this to line 19 of the details page:
var_dump($rsNEWUSER);
die($rsNEWUSER->getColumnVal("DCuserEMAIL"));
That should help you confirm that the recordset is returning the correct result. Once that is confirmed, then add this code below the email:
var_dump($_SESSION[$EmailRef."_From"]);
var_dump($_SESSION[$EmailRef."_To"]);
var_dump($_SESSION[$EmailRef."_Log"]);
die();
That should show you if it is trying to send the email and what it thinks the results are.