private function _validateHostnamePart()
    {
        $hostname = $this->_options['hostname']->setTranslator($this->getTranslator())
                         ->isValid($this->_hostname);
        if (!$hostname) {
            $this->_error(self::INVALID_HOSTNAME);

            // Get messages and errors from hostnameValidator
            foreach ($this->_options['hostname']->getMessages() as $code => $message) {
                $this->_messages[$code] = $message;
            }

            foreach ($this->_options['hostname']->getErrors() as $error) {
                $this->_errors[] = $error;
            }
        } else if ($this->_options['mx']) {
            // MX check on hostname
            $hostname = $this->_validateMXRecords();
        }

        return $hostname;
    }