Looking over include/payment_method.php I see:
Code:
$userinfo = array_merge($userinfo,$HTTP_POST_VARS);
So this may work:
{$userinfo.Customer_Notes}
If not try adding
Code:
$mail_smarty->assign("Customer_Notes",$HTTP_POST_VARS["Customer_Notes"]);
To the payment_method.php file. and try $Customer_Notes again in the mail template.
hth.
