IPN

IPN, short for Instant Payment Notification, is a messaging service from PayPal that notifies your store that a customer has paid for the items in his/her shopping cart. When this IPN message reaches your store, at this point the order is created within your store, causing emails to be sent and digital files to be prepared for download.

It is important to note that the IPN is not an email message or something that is intended for humans to read; a PayPal IPN is essentially code that one computer (PayPal) sends to another (your website's server).

This article discusses a technical topic that may not be intended for all readers. This article discusses configuration steps related to one or more third-party systems.

Ordering Process

These steps describe standard PayPal payments, not PayPal Express, which does not use IPN to create orders.

When a customer selects PayPal on the Checkout Page and submits the order, the following steps occur:

1. The customer is taken to PayPal to provide payment.
2. Once the customer has provided payment, two independent events happen:
   • The customer is returned to your store's thank-you page.
   • PayPal sends a message to your store.

The message that is sent to your store is the Instant Payment Notification. The IPN itself has a process before the order is created in your NeuCart system:

1. NeuCart receives the message and does some basic logging of the information.
2. NeuCart then sends a message back to PayPal, asking hey, is this IPN valid and actually sent from you?
3. PayPal responds with a message to say "Yes" or "No"

Valid IPN

If the IPN is valid (the usual case), NeuCart transforms the IPN into an order.

Invalid IPN

If the IPN is invalid (extremely rare), NeuCart sends an email to the store owner (email address configured in PayPal Preferences) with instructions for creating the order. For more information, see PayPal IPN Repost.

PayPal Account Configuration

PayPal changes their user interface frequently. If the steps below are no longer accurate, please contact NeuCart with the appropriate information so the page can show current information.

IPN must be enabled within the PayPal account that is configured to accept payments for the store (configured in PayPal Preferences). Follow these steps to enable IPN:

The notification URL that is entered in the PayPal Account is not used, but it must contain a valid URL to save. It is not used because each order sent to PayPal includes the IPN URL, and the inclusion of that field overrides the setting within this account configuration. Therefore, type any valid web address in this field, including something like http://anysite.com

1. Visit paypal.com and log in to your account.
2. Click [Profile] at the top of the page.
3. Click [Profile and settings]
4. Click [My Selling Tools].
5. Click [Update] next to "Instant payment notifications" in the "Getting paid and managing risk" section.
6. Enter the notification URL and select [Receive IPN messages].
7. Click [Save]

NeuCart Configuration

IPN-specific settings are configured in PayPal Preferences. These are mostly untouched by store owners except for the email address configuration. The configurable fields are:

Notification URL

This is the URL within your store where IPN messages will be sent; this field is configured automatically during installation and should not be altered without expert guidance. See the note, above, for an explanation of the interaction of these fields.

IPN Validation Method

An extremely technical field, this controls the method that is used to validate that an IPN is authentic. This field is provided because PayPal's validation methods may not always work in all environments. cURL is the recommended method, but it may require additional configuration to work if your website is hosted on a Windows operating system. HTTP POST generally works, but it has been known to fail occasionally in the PayPal sandbox environment.

IPN Log Email Address

The email address where IPN logs will be sent. A valid value should always be in this field.

IPN "From" Email Address

NeuCart's email generator can use any email address as the sending email address; this field allows configuration of the "from" email address used to send the IPN Log emails.

Send IPN Emails on Errors Only

If this is checked, the emails will be sent to the IPN Log Email Address only when an error occurs. If this is unchecked, both successful and unsuccessful IPN attempts will be emailed.

See also

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