When You <i>Really</i> Lose Customers They've changed e-mail addresses without telling you. But new services mean wayward clients aren't gone forever.

By all accounts, you're a good web marketer. When shoppers visit your website, you ask them to register, and then you dutifully collect their e-mail addresses. You also regularly send out e-mail messages that serve to market your products, services and seasonal promotions. You've done such a good job managing your company's e-mail mailing list, in fact, that sales have improved and you even have your best customers segmented to receive special promotions just for them.

Then, suddenly and without warning, your formula for success breaks down. Instead of receiving orders from eager customers wanting to buy your wares, you're hit with a mountain of electronic messages that have bounced back from expired accounts. Before long, "Undeliverable. User is not recognized" messages fill your inbox. Now you're left wondering if you'll find those great customers ever again. What's going on?