Form data taken via Ajax and POSTed to a PHP script for input into DB

This is probably very simple, but I'm really in over my head. Basically, I have a form with one input: email, and a submit button. This was not done by me so I understand very little of it. I tried to look up the .ajax jQuery command, but it still makes no sense.

Basically, here is what I have on the index.php.

The JS and HTML:

<!-- Subscription -->
<script>        
    $(function() {
        $('form input.submit').click(function (event) {
            event.preventDefault();
            event.returnValue = false;
            $.ajax({
                type: 'POST',
                url: 'subscribe.php',
                data: {email: $('form input[type=email]').val()},
                success: function(data) {
            开发者_运维问答        if (data == 'successful') {
                        $('#subscribe_status').html('Thanks for subscribing! We will let you know.').slideDown();
                    } else if (data == 'already_subscribed') {
                        $('#subscribe_status').html('This email is already subscribed.').slideDown();
                    } else if (data == 'invalid_email') {
                        $('#subscribe_status').html('This email is invalid.').slideDown();
                    } else {
                        $('#subscribe_status').html('Something went wrong. Please try again.').slideDown(); 
                    }
                },
                error: function () {
                    $('#subscribe_status').html('Subscription is not available.').slideDown();
                }
            });
        });
    });
</script>   
<form action="#">
    <input type="email" value="Your e-mail address..." onfocus="value=''" />
    <input type="submit" class="submit" value="Notify me" />
</form>

Subscribe.php

include 'go.php';
$email = $_POST['email'];
$ip=$_SERVER['REMOTE_ADDR'];
$timestamp = date("m/d/y H:i A");

mysql_query("INSERT INTO subscribers (ip, email, timestamp) VALUES (INET_ATON('$ip'), '$email', '$timestamp') ") or die(mysql_error());

I basically just keep getting "Something went wrong. Please try again."

Subscribe.php doesn't return anything, so data in your JS is always emtpy, hence the last else is always executed.