function validate($value)
 {
     $ret = true;
     if ($value && !Application::param('user_id')) {
         $user = new User();
         $user->clause('user_email', $value);
         if ($user->id()) {
             $ret = false;
             $this->setErrorMessage('A user with that email already exists');
         }
     }
     return $ret;
 }