You probably just left it out, but what was the effect on traffic to the website and as follow-on, sales? I'm thinking the goal was not to have more email subscribers, the goal was probably to sell more stuff via the website.
You're right to ask those questions -- on most sites it would be foolish to optimize for email subscribers at the cost of customers. In this case, however, it was a preview site and there was nothing to buy or download, so the most we could hope for was capturing the visitor's email.
