What is the Instant Payment Notification (IPN) timeout length?

Our Instant Payment Notification (IPN) service expects your webserver to send an HTTP 200 response when the IPN is sent to your script within 20 seconds. For retry attempts, we allow 30 seconds for a webserver to send an HTTP 200 response.

If your server doesn't respond after the initial attempt, the IPN service re-posts the IPN to your script. The amount of time between each re-post doubles each time - 10 seconds, 20 seconds, 40 seconds, 80 seconds, and so on, up to a maximum of 24 hours. The IPN service stops re-posting when:

• PayPal receives an HTTP 200 response from your webserver
• Approximately four days have passed since the initial post

This functionality applies to both Sandbox and Live account services.

See also:

How do I troubleshoot IPN?

Why didn't I receive any IPN posts?