global $current_user;
get_currentuserinfo();

if (class_exists('wpMail')) {
    $wpMail = new wpMail();
    global $Subscriber;

    $data = array(
        'email' => $current_user -> user_email,
        'list_id' => array(2),
        'mailinglists' => array(2),
        'firstname' => "Andrew",
        'lastname' => "Traub",
    );

    if ($Subscriber -> email_validate($current_user -> user_email) && $Subscriber -> optin($data, false)) {
        //success
    } else {
        print_r($Subscriber -> errors);
    }
}