save.php

if (isset($_POST['email']) && ($emailQuery->rowCount() === 0) ) {
//zdefiniowanie zmiennej $email
$email = filter_input(INPUT_POST, 'email', FILTER_VALIDATE_EMAIL);

//if email is not correct syntax
	if (empty($email)) {

//nie powiodlo sie echo $_POST['email']. "<br/>" .$email;
$_SESSION['given_email'] = $_POST['email'];
header('Location: index.php');

	} else {


//poprawny adres echo $_POST['email']. "<br/>" .$email;
// input into DB

	$query = $db->prepare('INSERT INTO users VALUES (NULL, :email)');
	$query->bindValue(':email', $email, PDO::PARAM_STR);
	$query->execute();
	}

} else {


	header('Location: index.php');
	exit();
}