PHP contact form email being received with no sender and email is not being populated in the body
<p>I am able to receive email with all the information except for the email address that is entered in the form, and when I receive the email, I get "No Sender" instead of the person's name. I am new to PHP and have done several Google searches but can't figure out what I am doing wrong. Please help. Thanks</p>

<p>This is my HTML:</p>

<pre><code>&lt;?php include("parts/doctype.php"); ?&gt;
</code></pre>

<p></p>

<pre><code>&lt;?php include("parts/header.php"); ?&gt;   

&lt;div class="page-wrap"&gt;

    &lt;?php include("parts/nav.php"); ?&gt;  

        &lt;div class="page-grid"&gt;

            &lt;h1 class="site-section-title"&gt;Contact Us&lt;/h1&gt;

            &lt;div class="content-area"&gt;

                &lt;form action="send-mail.php" method="POST"&gt;

                    &lt;div class="contactName"&gt;
                        &lt;h1 class="heading Name"&gt;Name&lt;/h1&gt;
                        &lt;label for="first-name" class="first_name"&gt;First Name&lt;/label&gt;
                        &lt;input type="text" id="first_name" name="first_name"  placeholder="Jane" autofocus required&gt;
                        &lt;label for="last_name" class="last_name"&gt;Last Name&lt;/label&gt;
                        &lt;input type="text" id="last_name" name="last_name" placeholder="Doe" required&gt;
                    &lt;/div&gt; &lt;!-- end name --&gt;

                    &lt;div class="number"&gt;
                        &lt;h1 class="heading"&gt;Phone Number&lt;/h1&gt;
                        &lt;label for="number" class="phone"&gt;Phone number&lt;/label&gt;
                        &lt;input type="tel" id="number" pattern="[0-9]{10}" name="sender_phone" placeholder="(###)-###-####"&gt;
                    &lt;/div&gt; &lt;!-- end number --&gt;

                    &lt;div class="email"&gt;
                        &lt;h1 class="heading"&gt;Email Address&lt;/h1&gt;
                        &lt;label for="email" class="emailLabel"&gt;Email&lt;/label&gt;
                        &lt;input type="email" name="sender_email" placeholder="janedoe@gmail.com" required&gt;
                    &lt;/div&gt;

                    &lt;div class="message"&gt;
                        &lt;h1 class="heading"&gt;Message&lt;/h1&gt;
                        &lt;label for="message"&gt;&lt;/label&gt;
                        &lt;textarea name="sender_message" id="message" cols="30" rows="10" spellcheck="true" required&gt; &lt;/textarea&gt;
                    &lt;/div&gt;

                    &lt;button id="submit" class="send"&gt;Send&lt;/button&gt;

                &lt;/form&gt;

            &lt;/div&gt; &lt;!-- end content area --&gt;

        &lt;/div&gt; &lt;!-- end grid --&gt;

    &lt;/div&gt; &lt;!-- end page wrap --&gt;
</code></pre>



<p>And this is my PHP:</p>

<pre><code>&lt;?php
$mail_to = 'removed address but I know it goes here'; // specify your email here

// Assigning data from the $_POST array to variables
$first_name = $_POST['first_name'];
$last_name = $_POST['last_name'];
$mail_from = $_POST['sender_email'];
$phone = $_POST['sender_phone'];
$message = $_POST['sender_message'];

// Construct email subject
$subject = 'Its time for a cupcake Message from visitor ' . $first_name;

// Construct email body
$body_message = 'From: ' . $first_name . $last_name . "\r\n";
$body_message .= 'E-mail: ' . $mail_from . "\r\n";
$body_message .= 'Phone: ' . $phone . "\r\n";  
$body_message .= 'Message: ' . $message;

// Construct email headers
$headers = 'From: ' . $first_name . "\r\n";

$headers .= 'Reply-To: ' . $mail_from . "\r\n";

$mail_sent = mail($mail_to, $subject, $body_message, $headers);


if ($mail_sent == true){ ?&gt;
    &lt;script language="javascript" type="text/javascript"&gt;
    alert('Thank you for the message. Should your message require a responce we will get back to you shortly.');
    window.location = 'contactus.php';
    &lt;/script&gt;
&lt;?php } else { ?&gt;
&lt;script language="javascript" type="text/javascript"&gt;
    alert('Message not sent. Please, try your message again. Should this still not work please contact use through facebook or twitter both links located on our home page.');
    window.location = 'index.php';
&lt;/script&gt;
&lt;?php
}
?&gt;
</code></pre>
