If you have access to the Address Verification System (AVS), use that as the first level of fraud screening. That will at least tell you if the card information matches the billing address.

AVS is not available for non-U.S. addresses, which makes foreign orders comparatively more risky.

Of course, the fact that the address matches the card information doesn't mean the card hasn't been stolen. So the next step -- and the first step for international orders -- is to contact the person the order is being billed to.

When you contact someone placing an order, it's important not to assume that the order is fraudulent. Sometimes suspect orders are actually from legitimate customers, and you would not want to offend them by seeming suspicious.

Start by checking that the billing address actually exists. When you retrieve orders online, you can check whether an address exists using Google Maps. Check also that the area code matches the address. If the order is a large one, or you feel uneasy about it, call the billing phone number to verify the information in the order. Ask the person who placed the order for home and work contact information, "in case there is a problem with the order."

You can also ask for the name and phone number of the bank that issued the card. Both are usually printed on the back.

If you are suspicious about an order, request that the customer give you a traceable ISP, business, or university email address, rather than an address at one of the free email services, like Gmail. Not all free email addresses are as obvious as Gmail. To find out whether an email address *@learn2yoga.com, for example, is a free address, go to www.learn2yoga.com and see if it is a site offering free email services.

If the order is from a foreign country, you may not want to make an international call to check out the order. In that case, you could send email instead.

As a general rule, someone using a stolen credit card number will not want to have a long conversation with you (especially in the U.S.).

Beware, though, that some criminals are very bold. We know of several cases where criminals have had extensive email conversations with merchants.

So what do you do with those suspicious orders? If you don't feel 100% certain about an order, simply ask for payment in advance before shipping--for example, by wire transfer.

Some stores go so far as not to ship outside the U.S., where AVS is available. That could be a valid approach if you are selling something with a high resale value, like gold coins.