how can i track mails to detect if it is opened or not and click links on it using mail function
$to=$mail['mail_to'] = $_POST['to'];
$subject=$mail['subject'] = validate($_POST['subject']);
$mail['message'] = makeLinks(validate($_POST['message']));
if ($add->add('mails', $mail)) {
$row = $se->get_last_Row('mails');
$message = $mail['message'];
$headers = "From: $from <" . $from . ">\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: text/html; charset=UTF-8\r\n";
$send = mail($to, $subject, $message,$headers);