Some of our IPN messages retries now have HTTP Status code 500 eventhough our IPN Listener is fully operational. Code 500 means they tried to call a thing that is not exist. This is a strong indication that their internet route configuration is faulty, and it possibly happen with only a group of servers or a range of IPs, in certain timeframe. Fixing internet route configuration is for a large scale service such as PayPal is not an easy task, unless they have a large group of dedicated engineers. For this reason, I believe this would not be fixed soon!
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