If you have an e-commerce selling credit card processing services account, the more you need to be conscious about preventing chargebacks or having to pay the cost of invalid credit card purchases. Therefore, additional security measures might be necessary for particularly suspicious transactions. Ask the customer to fax both sides of the card itself as well as any government ID such as a driver's license. Or require him to supply you with the Card Security Code which is a set of numbers found only on the credit card itself. Because most credit card theft happens virtually (only information about the account is stolen and not the card itself), knowing that a customer actually has the card increases the possibility that he is the legitimate card holder.

Spotting invalid purchases can actually be easy and may just require common sense. For example, orders to be shipped to an address other than what is indicated in a card holder's banking records could be illegal. Orders coming from free email services such as Yahoomail, Gmail, etc. are also a red flag considering the high incidence of fraud using these services.

Larger-than-normal purchases, especially when specified for rush shipment, could mean a thief grabbing the limited opportunity he has to drain his victim's account, knowing it will soon be frozen once the theft is reported. Orders made outside the country should also be looked into more closely simply because you will have practically no way of verifying whether or not the supplied address is genuine.