<!DOCTYPE html> <html> <body> <form method="get" action="https://www.cainiaomax.com/php/%3C?php%20echo%20htmlspecialchars($_SERVER%5B"PHP_SELF"]);?>"> E-mail: <input type="text" name="email"> <input type="submit" name="submit" value="Submit"> </form> <?php if (isset($_GET["email"])) { if (!filter_input(INPUT_GET, "email", FILTER_VALIDATE_EMAIL) === false) { echo("Email is valid"); } else { echo("Email is not valid"); } } ?> </body> </html>