1. if(is_numeric($email) && !empty($email)){
  2.     $email = $this->query("SELECT email FROM users WHERE id=".$email);
  3.     if($email && mysql_num_rows($email)>0){
  4.         $email = mysql_fetch_row($email);
  5.     $email = $email[0];
  6.     }
  7. }