联系表单用PHP发送空白数据

我最近为我的朋友创建了一个网站，其中包含一个使用PHP的联系人表单。当个人发送电子邮件时，数据不会通过电子邮件发送。

这是网站的代码

<article class="grid_8">
    <div class="indent-left">
        <h3 class="p1">Contact us</h3>
        <form id="contact-form" method="post" name="myemailform" action="contact_form.php">  
            <fieldset>
                <label><span class="text-form">Name:</span><input name="name" type="text" required /></label>
                <label><span class="text-form">Email:</span><input name="email" type="text" required /></label>                              
                <label><span class="text-form">Phone:</span><input name="phone" type="text" /></label>                              
                <div class="wrapper">
                    <div class="text-form">Message:</div>
                    <div class="extra-wrap">
                        <textarea name="message" required></textarea>
                        <div class="clear"></div>
                        <div class="buttons">
                            <input type="submit" value="Submit" class="button">
                        </div> 
                    </div>
                </div>                            
            </fieldset>                     
        </form>
    </div>
</article>

这是PHP 的代码

<?php
$name = $_POST['name'];
$message = $_POST['message'];
$phone = $_POST['phone'];
$email_from = $_POST['email'];
$email_subject = $_POST["New Message From www.chevroncreativesolutions.com"];
$email_body = $_POST["You have received a new message from $name.'n".
                     "Here is the message:'n $message.'n You Can call me on $phone.'n"].
$to = "matthias.mccarthy@gmail.com";
$headers = "From: $email_from 'r'n";
$contact_form=mail($to,$email_subject,$email_body,$headers);
if($contact_form) {
    echo "Message has been sent.";
    echo "<form><input type='button' value='Return back' onclick='history.back();'></form>";
} else {
    echo "Error In sending your message";
    echo "<form><input type='button' value='Return back' onclick='history.back();'></form>";
}