PHP - Help Me With Postback.php

Hello!
My enviroment: W2003 + MSSQL + PHP5 + IIS6.
Payment Gateway: Segpay.com

sent as .../payment/postback.php?action=Auth&purchaseid=25258400&tranid=30742324&email=techsean26%40segpay.com&TESTTRANS=1

My postback test page is simple, coded for minimize test errors,as:
if(isset($_GET["email"]))
{
    if($_GET['email']==""){
    $emailcust="'A'";
    }else{
    $emailcust = $_GET['email'];
    }       
}else{
$emailcust="nothing";
}
if(isset($_GET["purchaseid"]))
{
    if($_GET['purchaseid']==""){
    $IDpurchaseCust="'B'";
    }else{
    $IDpurchaseCust = $_GET['purchaseid'];
    }
}else{
$IDpurchaseCust="nothing";       
   
}


mssql_connect("myIP xxx.xxx.xxx.xxx", "myuser", "mypassword") or die("Server connection problems");
mssql_select_db("mydatabase") or die("Db selection problem");

$grava = mssql_query("INSERT INTO Transadas (email, purchaseID) VALUES('$emailcust','$IDpurchaseCust')");

Problem:

1) If I apply ."../payment/postback.php?action=Auth&purchaseid=25258400&tranid=30742324&email=techsean26%40segpay.com&TESTTRANS=1"
 on a browser like Internet Explorer, everything runs well and data inserted properly.

2) When Segpay postback, the url arrived as "."../payment/postback.php" effect. Segpay support claim that they really sent the full url exactly as above, and suggest that my server cannot receive a post from another server.

Waht I am missong on my code?

Tks for any suggestion 

I am trying to retrieve certain keys of a post array. I am sending a payment form with a dynamic number of product id's. I will never know how many product id's will be sent for each order. When the post array returns the values to my script it returns them as:

Code: [Select]
$_POST['product_id_1'], $_POST['product_id_2'], etc.
How would I be able to extract all post array keys that start with "product_id_? Here is what I was thinking earlier, but it doesn't work.

Code: [Select]
$i = 1;
foreach ($_POST['product_id_' . $i] as $product) {
    $productId = $product['product_id_' . $i];
    $queryInsert = mysql_query("INSERT INTO video_purchase (video_purchase_purchase_id, video_purchase_video_id) VALUES ($purchaseId, $productId)", $connect) or die(mysql_error());
    $i++;
}