/**
  * @return bool
  */
 public function checkInput()
 {
     global $lng;
     $ok = parent::checkInput();
     $query = ilUtil::stripSlashes($_POST[$this->getPostVar()]);
     if (!$ok) {
         return false;
     }
     include_once 'Services/Mail/classes/class.ilMailLuceneQueryParser.php';
     try {
         ilMailLuceneQueryParser::validateQuery($query);
         return true;
     } catch (Exception $e) {
         $this->setAlert($lng->txt($e->getMessage()));
         return false;
     }
 }