PHP form question

Hi - I have two different arrays of checkboxes in a form:

---------
<input name='service[]' value='abcde' type='checkbox' />
...

&

<input name='extra[]' value='abcde' type='checkbox' />
...
--------


There are also other form elements that I check and put into strings to eventually email like so:

--------
/Set recipient email
$myemail = "email@hotmail.com";

//See if the form has been submitted
if($_POST['submit']){    

 //Assign the text fields to variables
 $name = $_POST['name'];
 $position = $_POST['position'];
 $company = $_POST['company'];
 $address = $_POST['address'];
 $postcode = $_POST['postcode'];
 $phone = $_POST['phone'];
 $fax = $_POST['fax'];
 $email = $_POST['email'];
 $quote = $_POST['quote'];
 $further = $_POST['further'];
 $other = $_POST['other'];


 //Now to validate the form
 $errors = array();
 if($name == ""){
        array_push($errors, "You did not enter your name!");
 }
 if($email == ""){
        array_push($errors, "You did not enter an email address!");
 }
 else if(ereg("[A-Za-z0-9_-]+([.]{1}[A-Za-z0-9_-]+)*@[A-Za-z0-9-]+([.]{1}[A-Za-z0-9-]+)+", $email)) {
        $emailadd = "valid";
 }
 else {
        $emailadd = "invalid";
 }
 if ($emailadd == "invalid") {
        array_push($errors, "That does not appear to be a valid email address!");
 }

 //If there are no errors then send the email
 if(count($errors) == 0){
        $to = "$myemail";
        $subject = "Enquiry";
        $body = "Name: $name \n Email: $email \nPosition: $position \nCompany: $company \nAddress: $address \nPostcode: $postcode \nPhone no: $phone \nFax no: $fax  \n\n$quote ";
        $header = "From: $email";
        mail($to, $subject, $body, $header);
 }
}
?>
--------

Now, my question is, how do I add each selected checkbox and its' value into a string to email correctly? Taking into account that there are two groups of checkboxes?

Many thanks.