Ok I made the following change to the code which will now redirects the output with multiple results to another page.

This code is in my header file:

PHP Code:
$order_number=$_POST['order_number'];
  
$track_rs $db->Execute("SELECT tracking_number FROM fulfill_tracking WHERE order_number = " . (int)$order_number);
  if (
$track_rs ->RecordCount() == 1) {
    
$track_num $track_rs ->fields['tracking_number'];
header('Location: http://customurl.com/' $track_num);
  } elseif (
$track_rs ->RecordCount() > 0) {
$_SESSION['order_number'] = $order_number;
      
zen_redirect(zen_href_link(FILENAME_TRACKING'action=trackingInfo'));
  
  } else {
      
$messageStack->add('tracking'ENTRY_ORDER_NUMBER_ERROR3);
  } 
This code is in my templates file:

PHP Code:
<?php
  
if (isset($_GET['action']) && ($_GET['action'] == 'trackingInfo')) {
?>
<div class="mainContent trackingInfo"></div>

<?php
$order_number 
$_SESSION['order_number'];
  
$track_rs $db->Execute("SELECT tracking_number FROM fulfill_tracking WHERE order_number = " . (int)$order_number);
 if (
$track_rs ->RecordCount() > 0) {
    
$track_num = array();
    while(!
$track_rs->EOF) {
      
$track_num[] = $track_rs ->fields['tracking_number'];
      
$track_rs->MoveNext();
}
echo 
'<p class="trackingInfoBoxes">This order shipped in ' sizeof($track_num). ' box' .(sizeof($track_num) != 'es' '') . ':</p>';
echo 
"\n";
foreach (
$track_num as $key => $val) {
  echo 
'<p class="trackingInfoPackages">Package ' . ($key+1) . ':  <a href="http://customurl.com/' $val '">Click to Track</a></p>';
  echo 
"\n";
}
  }
?>
It works not sure if there is a better way of doing it though. Thanks again for the help!