Hello, this message is replied from server (https://online.verypdf.com), you can control or track PDF documents from Web Server easily. ABC; function MyDebugLogWithLine($strFileLine, $text) { // open log file $filename = rtrim($_SERVER['DOCUMENT_ROOT'], DIRECTORY_SEPARATOR) . "/log/pdftracker.log"; if(file_exists($filename)) { if(filesize($filename) > 1024*1000) { $fh = fopen($filename, "w"); fclose($fh); } } $fh = fopen($filename, "a") or die("Could not open log file ($filename)."); fwrite($fh, date("Y-m-d H:i:s") . " $strFileLine - $text\n") or die("Could not write file ($filename)!"); fclose($fh); $text = str_replace("\n", "
", $text); } ?>