How long is the IPN timeout length?
If your server doesn't respond after a certain amount of time, the IPN system then 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 system stops re-posting when:
- PayPal receives a basic HTTP "200 OK" response from your web server, or
- When approximately four days have passed since the initial post.
Note: This functionality applies to both Sandbox and Live accounts.
See also:
How do I troubleshoot IPN?
Why didn't I receive any IPN posts?