Sophisticated online subscription marketers, Classmates has an ongoing series of emails that go out its membership offer abandoners -- visitors who got part-way through the steps of signing up for a membership but abandoned when asked for a credit card number.(Note: our Insider's Marketing Samples Library has several examples of email series sent to abandons by various subscription site marketers.)Classmates sends its emails several times a week -- up to months after a consumer has abandoned. I ...