I have the following contact form, using PHP, JS and a bit of Ajax. I want to make sure that it is secure.<?phpsession_start();if ($_SERVER['REQUEST_METHOD'] == 'POST'){    ob_start();        if(isset($_POST['name']) && isset($_POST['email']) && isset($_POST['message']) && isset($_POST['token']))        {            if($_SESSION['token'] != $_POST['token'])            {                $response = 0;            }            else            {                $_SESSION['token'] = ;                $name = $_POST['name'];                $email = $_POST['email'];                $message = $_POST['message'];                $to = email@here.com;                $subject = New Message From: $name;                $message = $message;                $headers  = 'MIME-Version: 1.0' . \r\n;                $headers .= 'Content-type: text/html; charset=utf-8' . \r\n;                $headers .= 'From: '.$email . \r\n;                $mailed = ( mail($to, $subject, $message, $headers) );                if( isset($_POST['ajax']))                    $response = ($mailed) ? 1 : 0;                else                    $response = ($mailed) ? <h2>Success!</h2> : <h2>Error! There was a problem with sending.</h2>;                echo $response;            }        }        else        {            echo Form data error!;        }    ob_flush();    die();}?><!DOCTYPE html><html class=no-js>    <head>        <title>Contact us | Website Name</title>        <meta name=description content=>        <?php include (assets/includes/header.inc); ?>    </head>    <body>        <header id=headerWrapper>            <div id=headerContent>                <div id=headerLogo><!--Logo-->                    <?php include (assets/includes/header-logo.inc); ?>                </div>                <nav><!--Main Menu-->                    <ul id=mainMenu>                        <?php include (assets/includes/menu.inc); ?>                    </ul>                </nav>            </div>        </header>        <!--Header (small screens only)-->        <?php include (assets/includes/second-header.inc); ?>        <div id=page><!--Page Container-->            <div id=contactPage class=wrapper>                <div class=content>                    <!--Contact Form-->                    <?php                        $token = md5(uniqid(rand(), TRUE));                        $_SESSION['token'] = $token;                    ?>                    <form id=contactForm action=contact.php method=post name=contactForm>                        <input id=token type=hidden value=<?php echo $token; ?> />                        <div class=name>                            <label>Your Name</label>                            <input id=name type=text placeholder=Enter Name required>                        </div>                        <div class=email>                            <label>Email Address</label>                            <input id=email type=email placeholder=Enter Email required>                        </div>                        <div class=message>                            <label>Message</label>                            <textarea id=message required></textarea>                        </div>                        <button id=submit type=submit>Send</button>                    </form>                    <script type=text/javascript>                    $(#contactForm).submit(function(event) {                        /* stop form from submitting normally */                        event.preventDefault();                        /* get some values from elements on the page: */                        var $form = $(this),                            $submit = $form.find('button[id=submit]'),                            token_value = $form.find('input[id=token]').val(),                            name_value = $form.find('input[id=name]').val(),                            email_value = $form.find('input[id=email]').val(),                            message_value = $form.find('textarea[id=message]').val(),                            url = $form.attr('action');                        /* send the data using post */                        var posting = $.post(url, {                            token : token_value,                            name : name_value,                            email : email_value,                            message : message_value,                            ajax : 1                        });                        posting.done(function(data) {                            $form.find('span.error').remove();                            if (data == 1) {                                /*Change the button text.*/                                $submit.text('Sent. Thank You!');                                $submit.addClass(sent);                                $(#submit).attr('disabled', 'disabled');                            } else {                                $submit.after('<span style=display: inline-block; padding: 20px 5px; color: #bd3d3d class=error>Failed to send the message, please try again later.</span>');                                /*Change the button text.*/                                $submit.text('Try Again');                            }                        });                    });                    </script>                    <!--Contact Details Section-->                    <div id=contactDetails>                        <div>                            <h3><strong>Contact Details</strong></h3>                                <br>                            <p><strong>Telephone:</strong> +44 00 0000000</p>                            <p><strong>Email:</strong> email@email.com</p>                            <!--Phone contact buttons-->                            <div class=hidden>                                <a href=tel:0044000000000>Tap to call us</a>                                <a href=sms:0044000000000>Tap to send us a SMS</a>                            </div>                        </div>                        <!--Social Icons-->                        <br><div class=socialbar>                            <p><strong>Find us on:</strong></p>                            <a href=# target=blank class=icon-facebook></a>                            <a href=# target=blank class=icon-linkedin></a>                            <a href=# target=blank class=icon-twitter></a>                            <a href=# target=blank class=icon-youtube></a>                        </div>                    </div>                </div>            </div>            <!--Footer-->            <footer id=footer>                <?php include (assets/includes/footer.inc); ?>            </footer>        </div><!--The End Of The Page-->        <!--Scripts Links-->        <?php include (assets/includes/scripts.inc); ?>    </body></html>
Is this contact form secure?
php;security;ajax;form