in
mail("$email", "An HTML Message", "", $headers);
you have the message field empty, how do you set message value?.
mail("$email", "An HTML Message", "$message", $headers);
before mail()
$message="<html><body><table width='680' border='4' align='centre' cellpadding='0' cellspacing='0' bordercolor='#257690' bgcolor='#257690'></body></html>";
with "Content-Type: text/html; charset=ISO-8859-1\r\n" .
the html tags will be picked up and displayed correctly.
if you are using a textarea as opposed to a bulk email
<tr>
<td> </td>
<td align="left" valign="top">Message:</td>
<td height="25" align="left" valign="top" class="text">
<textarea name="message" rows="10" cols="30" value="$message"></textarea></td></tr>
and before mail() use
$message = nl2br($message);
to include new line breaks http://uk.php.net/manual/en/function.nl2br.php