Someone says that my PHP code is vulnerable to XSS. I asked them what I should do to fix it, but now they don't want to help.$action=$_REQUEST['action'];                /* send the submitted data */    {    $name=$_REQUEST['name'];    $email=$_REQUEST['email'];    $message=$_REQUEST['message'];    if (($name==)||($email==)||($message==))        {        echo All fields are required, please fill <a href=\\>the form</a> again.;        }    else{                $from=From: $name<$email>\r\nReturn-path: $email;        $subject=Message sent using your contact form;        mail(email@website.com, $subject, $message, $from);        echo Email sent!;        }    }  ?> 
PHP form-to-email script
php;security;email