Ask HN: What are some things to look out for fraud in ecommerce application

Here is some of the things which I can think of but wanted to get more thoughts...

[1] Unusually large orders or high-priced orders

[2] Expedited shipping on large quantities or high-priced orders

[3] Expedited shipping when billing and shipping addresses differ

[4] Make sure the billing address matches the IP location.

(5) Limit the number of declined transactions.

(6) Customers who make multiple orders from different credit cards

(7) Machine Learning - supervised classification - the system is told in advance which already-reviewed orders are fraud, and then asked to predict whether another order is fraud based on what it’s seen so far

(8) Anomaly detection