php form mail script

I've been using a form mail script from CosmicPHP for a while now, it was the only thing that I got to work on my server. The emails I recieved came from the email address no_reply@itweb.no (IT Web is my domain host). But now ITweb has hooked up with another host and they recently closed the itweb server, so I am not recieving the emails since the sender address does not exist.

I looked at the script to see where I would specify the sender address but I couldn't find it. I included the two files the script uses below in the lovely cuts.


<?

include('config.php');

global $emailfield;
global $required;
global $sentmessage;
global $toemail;
global $fields;
global $subject;


$msg = array($name, $email, $message);
$name = 'name';
$email = 'email';
$message = 'message';

$headers = "MIME-Version: 1.0\r\n";
$headers .= "Content-type: text/html; charset=iso-8859-1\r\n";

$filename = "email.htm";
$handle = fopen ($filename, "r");
$contents = fread ($handle, filesize ($filename));
fclose ($handle);

foreach ($fields as $field)
{
$entry = $_POST[$field];
if (!$entry) $entry = "No data submitted";
$contents = str_replace ("::$field::",$entry,$contents);
}

mail($toemail, $subject, $contents, $headers);

$filename = "sent.htm";
$handle = fopen ($filename, "r");
$contents = fread ($handle, filesize ($filename));
fclose ($handle);

$contents = str_replace ("::SentMessage::",$sentmessage,$contents);

echo $contents;
?>


<?

## fields contains all the variables from the form to be sent in the email - CaSe SeNsItIvE
$fields = array('email','episode');

## required contains all the variables that MUST be filled in - CaSe SeNsItIvE
$required = array();

## emailfield contains the name of the variable to be validated as an email address
$emailfield = "Email";

## subject of the email to be sent
$subject = 'Quote Quiz Results';

## email address to send responses to
$toemail = 'kristine@perander.no';

## message displayed when email has been sucessfully sent
$sentmessage = "Your message has been sent."
?>

So my question is this; is it possible to add something to the script that spesifies a sender address and put one of my addresses there (and is it easy?), or should I look for a new script? My php knownledge: It is safe to let me customize it but not code it myself:p