问弹出窗口和PHP表单

EN

<!------Contact Page------->

<form method='post' action='sendemail.php' >
    <label>Name</label>
    <input name="name" placeholder="Type Here">
    <label>Email</label>
    <input name="email" placeholder="Type Here" id="email">
    <label>Message</label>
    <textarea name="message" placeholder="Type Here"></textarea>


    <label>Human Verification</label>
      <input name="human" placeholder="2 + 2 = ? " id="human">
      <input id="submit" name="submit" type="submit" value="Submit">
    </label>     
</form>

<?php
    $name = $_POST['name'];
    $email = $_POST['email'];
    $message = $_POST['message'];
    $from = $email; 
    $to = 'my@email.com'; 
    $subject = 'New Message';
    $human = $_POST['human'];

    $body = "From: $name\n E-Mail: $email\n Message:\n $message";

    if ($_POST['submit']) {
        if ($name != '' && $email != '') {
            if ($human == '4') {                 
                if (mail ($to, $subject, $body, $from)) { 
                    echo '<h4>Your message has been sent!</h4>';
            } else { 
                echo '<h4>Something went wrong, go back and try again!</h4>'; 
            } 
        } else if ($_POST['submit'] && $human != '4') {
            echo '<h4>You answered the anti-spam question incorrectly!</h4>';
            }
        } else {
            echo '<h4>You need to fill in all required fields!!</h4>';
        }
    }
?>