Retrieve Checkbox Array in PHP and Send in Email

I'm trying to feed the following checkboxes through to a PHP email form:

<div id="product_information_container">
    <h1 id="product_information_subtitle"><a data-tooltip="Click to hide/display the content below." href="#"><img class="information_icons" src="images/information_icon.png"></a>What can we help you with?</h1>
    <div class="product_information">
        <div class="product_information_containers" id="product_information_attic_barrier">
            <input id="product_information_checkbox_attic_barrier" name="product_information[]" type="checkbox" value="attic_barrier" />
            <span class="product_options">Attic Barrier</span>
        </div>
    </div>
    <div class="product_information">
        <div class="product_information_containers" id="product_information_doors">
            <input id="product_information_checkbox_doors" name="product_information[]" type="checkbox" value="entry_system_door" />
            <span class="product_options">Entry System Door</span>
        </div>
    </div>
    <div class="product_information">
        <div class="product_information_containers" id="product_information_eavestrough_cover">
            <input id="product_information_checkbox_eavestrough_cover" name="product_information[]" type="checkbox" value="eavestrough_cover" />
            <span class="product_options">Eavestrough Cover</span>
        </div>
    </div>
    <div class="product_information">
        <div class="product_information_containers" id="product_information_windows">
            <input id="product_information_checkbox_windows" name="product_information[]" type="checkbox" value="windows" />
            <span class="product_options">Windows</span>
        </div>
    </div>
    <div class="product_information" id="window_options">
        <div id="windows_options_one">
            <div class="product_information_windows_containers" id="product_information_windows_baybow">
                <input id="windows_baybow_checkbox" name="product_information[]" type="checkbox" value="windows" />
                <span class="product_options">Bay/Bow</span>
            </div>
            <div class="product_information_windows_containers" id="product_information_windows_casement">
                <input id="windows_casement_checkbox" name="product_information[]" type="checkbox" value="windows" />
                <span class="product_options">Casement</span>
            </div>
        </div>
        <div id="windows_options_two">
            <div class="product_information_windows_containers" id="product_information_windows_doublehung">
                <input id="windows_doublehung_checkbox" name="product_information[]" type="checkbox" value="windows" />
                <span class="product_options">Double-Hung</span>
            </div>
            <div class="product_information_windows_containers" id="product_information_windows_sliding">
                <input id="windows_sliding_checkbox" name="product_information[]" type="checkbox" value="windows" />
                <span class="product_options">Sliding</span>
            </div>
        </div>
    </div>
</div>

I then intend to capture the information entered, and notify which pieces of information are relevant. Essentially, all products selected within "product_information" should be fed through, if checked. However, with my current code, I only receive the last value selected in the group of checkboxes.

Here is my PHP code:

<?php  
if(isset($_POST)){
    $ip_address = $_SERVER['REMOTE_ADDR'];
    $date = date('d/m/Y');
    $time = date('H:i:s');

    $first_name = $_POST['first_name'];
    $spouse_name = $_POST['spouse_name'];
    $last_name = $_POST['last_name'];
    $street_number = $_POST['street_number'];
    $street_name = $_POST['street_name'];
    $street_type = $_POST['street_type'];
    $city = $_POST['city'];
    $postal_code = $_POST['postal_code'];
    $phone_number = $_POST['phone_number'];
    $alternate_phone_number = $_POST['alternate_phone_number'];
    $email_address = $_POST['email_address'];
    $contact_time = $_POST['contact_time'];
    $product_information = $_POST['product_information'];

    $headers = "From: [email protected]" . "\r\n";  
    $headers .= 'Content-type: text/html; charset=iso-8859-1' . "\r\n";  

    $emailbody = "<p>You have received a message!</p> 
                  <strong>Name: </strong>{$first_name} {$last_name}, <strong>Spouse's Name: </strong>{$spouse_name}<br />
                  <strong>Address: </strong>{$street_number} {$street_name} {$street_type}, {$city}, ON {$postal_code}<br />
                  <strong>Phone Number: </strong> {$phone_number}, <strong>Alt. Phone Number: </strong> {$alternate_phone_number}<br />
                  <strong>Email Address: </strong> {$email_address}</p>
                  <p>Please contact {$first_name} during the {$contact_time} about {$product_information}.<br
                  <p>This message was sent from the IP Address: {$ip_address} on {$date} at {$time}.</p>";  

    mail('[email protected]','Title',$emailbody,$headers);
}
?>