User Guide

IPN Guide June, 2009 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.
z What is IPN?
z IPN Protocol and Architecture
z A Sample IPN Message and Response
z Non-IPN Notification Mechanisms
What is IPN?
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. These events include the
following:
z Instant payments, including Express Checkout and direct credit card payments
z eCheck payments and associated status, such as pending, completed, or denied
z Payments that may be pending for other reasons, such as those being reviewed for potential
fraud
z Events related to recurring payments and subscriptions
z Authorizations, which indicate a sale whose payment has not yet been collected
z Chargebacks, which are initiated by a credit card processor; for example, when a customer
disputes a charge
z Disputes, which are initiated by a buyer using the PayPal resolution process
z Reversals, which occur when you win a dispute or a chargeback is canceled
z Refunds, which you may choose to give
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