PHP: Accents in Email Subject

function encode_iso88591($string){

  $text = '=?iso-8859-1?q?';

  for( $i = 0 ; $i < strlen($string) ; $i++ ){

    $val = ord($string[$i]);

    $val = dechex($val);

    $text .= '='.$val;

  }

  $text .= '?=';

  return $text;

}