Zend_Mail::setHeaderEncoding PHP Méthode

    public function setHeaderEncoding($encoding)
    {
        $allowed = array(Zend_Mime::ENCODING_BASE64, Zend_Mime::ENCODING_QUOTEDPRINTABLE);
        if (!in_array($encoding, $allowed)) {
            /**
             * @see Zend_Mail_Exception
             */
            require_once 'Zend/Mail/Exception.php';
            throw new Zend_Mail_Exception('Invalid encoding "' . $encoding . '"');
        }
        $this->_headerEncoding = $encoding;
        return $this;
    }

 public static function execute($subject, $to, $from, $body)
 {
     sfOpenPNEApplicationConfiguration::registerZend();
     $subject = mb_convert_kana($subject, 'KV');
     $mailer = new Zend_Mail('iso-2022-jp');
     $mailer->setHeaderEncoding(Zend_Mime::ENCODING_BASE64)->setFrom($from)->addTo($to)->setSubject(mb_encode_mimeheader($subject, 'iso-2022-jp'))->setBodyText(mb_convert_encoding($body, 'JIS', 'UTF-8'), 'iso-2022-jp', Zend_Mime::ENCODING_7BIT);
     $result = $mailer->send();
     Zend_Loader::registerAutoLoad('Zend_Loader', false);
     return $result;
 }