|Index||-||FAQ - Cart Help Buttons - Cart Settings - 8. Advanced Settings|
Field 11: itemsilentpost (optional) gives the ability to have the shopping cart send your servers instant notification that an order has processed.
Any text entered into this Verification Text field will be sent with every ItemSilentPost connection. You can use this to authenticate that the order is from the shopping cart, and not from another party.
The shopping cart will also expect this value to be returned on every connection. If it is not returned, then a warning message will be printed on your merchant receipt (your customers will not see the warning).
The name of this parameter is: ItemSilentPostVerification.
Note: ItemSilentPost can only to connect on port 80 or port 443. Please make sure your developers use these ports for communication.