What is retry policy for Apple Server-to-Server Notifications

Question

I'm implementing server-side application that manages subscriptions for IOS application. To control account state(subscription is active or not) on the backend I'm using Apple Server-to-Server Notifications

Documentation saying:

Respond to Server-to-Server Notifications Your server should send an HTTP status code to indicate whether the server-to-server notification post succeeded:

Send HTTP 200 if the post was successful. Your server is not required to return a data value.

Send HTTP 50x or 40x to have the App Store retry the notification if the post was not successful. The App Store makes several attempts to retry the notification over a period of time but eventually stops after continued failed attempts.

But it is not clear which exactly retry policy apple following in case of server error on my side. I'm looking for the answer to the following questions

1. How many retries apple will do?
2. With which interval between retries?

Answer 1

The retry policy for App Store server notifications depends on the version of the server notification. It retries as follows:

• For version 1 notifications, it retries three times; at 6, 24, and 48 hours after the previous attempt.
• For version 2 notifications, it retries five times; at 1, 12, 24, 48, and 72 hours after the previous attempt.

See here for details.