AMP-表单不使用PHP发送邮件

Question

我使用了以下代码。问题是，在我的AMP网站中，单击“ PHP POST”后按钮无法交互->我无法通过单击“提交”按钮来执行代码

if (isset($_POST['submit'])) {
    $to = "mail@domain.com"; // this is your Email address
    $from = $_POST['email']; // this is the sender's Email address
    $first_name = $_POST['first_name'];
    $last_name = $_POST['last_name'];
    $subject = "Form submission";
    $subject2 = "Copy of your form submission";
    $message = $first_name . " " . $last_name . " wrote the following:" . "\n\n" . $_POST['message'];
    $message2 = "Here is a copy of your message " . $first_name . "\n\n" . $_POST['message'];

    $headers = "From:" . $from;
    $headers2 = "From:" . $to;
    mail($to, $subject, $message, $headers);
    mail($from, $subject2, $message2, $headers2); // sends a copy of the message to the sender
    echo "Mail Sent. Thank you " . $first_name . ", we will contact you shortly.";
    // You can also use header('Location: thank_you.php'); to redirect to another page.
}
?>

<form action="" method="post">
    First Name: <input type="text" name="first_name"><br>
    Last Name: <input type="text" name="last_name"><br>
    Email: <input type="text" name="email"><br>
    Message:<br><textarea rows="5" name="message" cols="30"></textarea><br>
    <button type="submit" name="submit" value="Submit">BUTTON</button>
</form>