It might work better if you did something like this:
<?php
$msg = "Sender's Name:\t{$_POST['sender_name']}\n";
$msg .= "Sender's E-mail:\t{$_POST['sender_email']}\n";
$msg .= "Favorite Page(s):\t{$_POST['favorite']}\n";
$msg .= "Message Topic:\t{$_POST['topic']}\n";
$msg .= "Message:\t{$_POST['message']}\n\n";
$mailheaders = "From:\t{$_POST['sender_name']}<paul@kingworks.net>\n";
$mailheaders .= "Reply-To: $sender_email\n\n";
mail("pauking1@juno.com", "KINGWORKS", $msg, $mailheaders);
echo "<h1 align=center>Thank You, $_POST[sender_name]</h1>";
echo "<p align=center>I appreciate your visit, and hope to reply soon!</p>";
?>
If that doesn't help, I'd double check the form that is submitting the information and make sure that the field is named 'favorite.'