public function testWrongUniqueId()
 {
     $mail = new Zend_Mail_Storage_Pop3($this->_params);
     try {
         $mail->getNumberByUniqueId('this_is_an_invalid_id');
     } catch (Exception $e) {
         return;
         // test ok
     }
     $this->fail('no exception while getting number for invalid id');
 }