联系表单错误Msg / JS PHP

I'm working on a contact form on anniebest.co.za which has the following code. It was part of the site before I did some simple changes but has never worked. Can anyone see the problem here so I can avoid having to completely re-code the form?

This is the error message i get: Internal Server Error

The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator, webmaster@anniebest.flightcentre.ie and inform them of the time the error occurred, and anything you might have done that may have caused the error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

<script type="text/javascript">
$(document).ready(function () {
    $(function () {
        "use strict";
             $('#contact_form').submit(function (e) {
               e.preventDefault();
               var form = $(this);
               var name = $("#name").val();
               var email = $("#email").val();
               var text = $("#message").val();
               var dataString = 'name='+name+'&email='+email+'&message='+ text;
                function isValidEmail(emailAddress) {
                    var pattern = new RegExp(/^((([a-z]|\d|[!#\$%&'\*\+\-
    \/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])+(\.([a-z]|\d|   
    [!#\$%&'\*\+\-\/=\?\^_`{\|}~]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-
    \uFFEF])+)*)|((\x22)((((\x20|\x09)*(\x0d\x0a))?(\x20|\x09)+)?(([\x01-
    \x08\x0b\x0c\x0e-\x1f\x7f]|\x21|[\x23-\x5b]|[\x5d-\x7e]|[\u00A0-
    \uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(\\([\x01-\x09\x0b\x0c\x0d-\x7f]|
    [\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF]))))*(((\x20|\x09)*(\x0d\x0a))?
     (\x20|\x09)+)?(\x22)))@((([a-z]|\d|[\u00A0-\uD7FF\uF900-
     \uFDCF\uFDF0-\uFFEF])|(([a-z]|\d|[\u00A0-\uD7FF\uF900-
     \uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-\uD7FF\uF900-
    \uFDCF\uFDF0-\uFFEF])*([a-z]|\d|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-
    \uFFEF])))\.)+(([a-z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])|(([a-
    z]|[\u00A0-\uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])([a-z]|\d|-|\.|_|~|[\u00A0-  
    \uD7FF\uF900-\uFDCF\uFDF0-\uFFEF])*([a-z]|[\u00A0-\uD7FF\uF900-
    \uFDCF\uFDF0-\uFFEF])))\.?$/i);
                    return pattern.test(emailAddress);
                };
                if (isValidEmail(email) && (text.length > 20) && (name.length > 1)) {
                    $.ajax({
                        type: 'POST',
                        url: "contact_form/contact_process.php",
                        data: dataString,
                        success: function () {
                            $('.success').fadeIn(1000);
                        }
                    });
                } else {
                    $('.error').fadeIn(1000);
                }
            });
        });
    });
</script>

<!-- the php file -->

<?php
$to = "anniebest8787@gmail.com";
$name = $_POST['name'];
$message = $_POST['message'];
$from = $_POST['email'];
$headers = "From:" . $from;
mail($to,$name,$message,$headers);
echo "Mail Sent.";
?>