$url = "google.com";
 $ch = curl_init("$url");
            curl_setopt($ch,
            CURLOPT_RETURNTRANSFER, 1);
            curl_setopt($ch, CURLOPT_HEADER, 1);
            curl_setopt($ch,
            CURLOPT_FOLLOWLOCATION, 1);
            $output = curl_exec($ch);
            if ($output === false || strstr
            ($output, "HTTP/1.1 404")){//Since server supplies a valid HTML file for missing URLS, also need to look for 404 error in output.
                $out['content'] .= "<p>URL $url in the
                html mail doesn't appear to exist.</p>";
                $badlink = true;
                } else {
                $out['content'] .= "<p>URL <a
                href='$url' target='_new'>$url</a> found</p>";
            }
            echo $out['content'];