List of web-hook's response statuses
Shifter's web-hook standards with HTTP response status code
Here are well-known statuses and their means.
20x: Success. No retry.
30x: Follow redirect once, if it gets 30x response again, mark it fails. No retry.
40x: Fail. No retry.
50x: Fail. Try to resend.
Connection error: Try to resend.
Maximum counts of retries are 5 times.
Session time out is 5 seconds.