use this code for the business tag to set it dynamicly based on the post code:
<?php
$ppBusiness = "";
switch(isset($_POST['postcode'])?$_POST['postcode']:"") {
case "12345":
$ppBusiness = "one@one.com";
break;
case "678910":
$ppBusiness = "two@two.com";
break;
default:
$ppBusiness = "default@default.com";
break;
}
?>
<input type="hidden" name="business" id="business" value="<?php echo($ppBusiness); ?>" />