U.S. Stores Learn the Ropes of Shipping to Foreign Shoppers @ NYTimes.com.

“Typically the guys we’re talking to start off thinking they can toss it in a box and give it to U.P.S. or FedEx and hope it gets there,” said Michael DeSimone, chief executive of FiftyOne, a technology company that helps retailers add international shipping capabilities.

But there are problems with ordering systems, customs and postal fees, he said.

For example, many retailers do not have software in their warehouse management systems that recognizes foreign postal codes, which — unlike those in the United States — do not always have five digits.
“It sounds like a really stupid reason not to sell internationally,” Mr. DeSimone said, “but I can’t tell you how many times I’ve heard this was the biggest roadblock.”