2012

IPN Guide July 10, 2012 7
1
Introducing IPN
Instant Payment Notification (IPN) is a message service that notifies you of events related to
PayPal transactions. You can use it to automate back-office and administrative functions, such
as fulfilling orders, tracking customers, and providing status and other information related to a
transaction.
 IPN Overview
 IPN Protocol and Architecture
 A Sample IPN Message and Response
 Non-IPN Notification Mechanisms
IPN Overview
IPN notifies you when an event occurs that affects a transaction. Typically, these events
represent various kinds of payments; however, the events may also represent authorizations,
Fraud Management Filter actions and other actions, such as refunds, disputes, and
chargebacks.
IPN is a message service that PayPal uses to notify you about events, such as:
 Instant payments, including Express Checkout, Adaptive Payments, and direct credit card
payments, and authorizations, which indicate a sale whose payment has not yet been
collected
 eCheck payments and associated status, such as pending, completed, or denied, and
payments pending for other reasons, such as those being reviewed for potential fraud
 Recurring payment and subscription actions
 Chargebacks, disputes, reversals, and refunds associated with a transaction
In many cases, the action that causes the event, such as a payment, occurs on your website;
however, your website is not the only source of events. In many cases, events can be generated
by Website Payment Standard buttons, the PayPal API, or by PayPal itself.
You detect and process IPN messages with a listener, sometimes called a handler, which is a
script or program that you write. It waits for messages and passes them to various back-end or
administrative processes that respond the messages. PayPal provides sample code that you can
modify to implement a listener that detects IPN messages.
The actions to take when your listener is notified of an event are specific to your needs.
Examples of the kinds of actions you might take when your listener receives an IPN message
include the following: