Notifications have to be sent through a SMTP Cluster, which has limit capacity of 1000/second. Ordering system requires latency below 5 seconds, and has peak TPS 500/second. Ship confirm requires latency below 24 hours, and has peak TPS 500/second. Flash sales requires latency below 2 hours, need to be sent 2/3 times per week, 1MM customers each time. Invoicing requires latency below 72 hours; Peak TPS 500/second