public function extractAuthor($string)
    {
        preg_match_all('/[\._a-zA-Z0-9-]+@[\._a-zA-Z0-9-]+/i', $string, $matches);
        $string = str_replace($matches[0], '', $string);
        $string = str_replace(['<', '>', '()'], '', $string);
        $string = trim($string);

        return empty($string) ? 'Unknown' : $string;
    }