Formmail som html mail?

Denne kode skulle gerne sende en html mail. Men det virker ikke, det er bare koden den sender, hvad er galt ???

Hilsen
Rubaek

if(isset($sendmail)) {
$message = "<!DOCTYPE HTML PUBLIC '-//W3C//DTD HTML 4.0 Transitional//EN'>
<HTML><HEAD><TITLE>TEST</TITLE><META Content-Type content='text/html; charset=windows-1252'></HEAD><BODY BGCOLOR='#408080'>Dette er en test side</BODY></HTML>";
mail($recipient, $subject, $message, $headers);
}
?>
<form action="<?=$PHP_SELF ?>" method="post">
<table><tr><td>Modtager (email):</td><td><input type="text" name="recipient" size="60"></td></tr><tr><td>Overskrift:</td><td><input type="text" name="subject" size="60"></td></tr><tr><td>Tekst:</td><td><textarea name="message" cols="80" rows="8"></textarea></td></tr><tr><td><b>»</b></td><td><input type="submit" name="sendmail" value="Send mail"></td></tr></table></form>