Score your users based on attributes like whats in cart, IP reputation, browser/os, pages visited, source,3rd party fraud detecton providers etc. Score should reflect how likely the user is genuine or not. For well scoring users which should be 90% of your traffic, provide them with detailed messages.
I wish sites like newegg would treat customs with successful transactions as safe. I've had many times where they've outright canned an important order for really no reason. Trying to get them to accept it is a whole other hassle.
I have been. Despite it sometimes costing more I buy all my drives from other vendors. Mostly been amazon recently. They're cool with taking my huge orders.
