And then one day Barnes and Nobles puts couches and cafes in the stores and practically begged people to read books in their store without buying them. Now you've got all these customers sitting in their stores for hours at a time, mittengrabben all the books with their filthy hands, and the probability that they find something they want to buy is linearly proportional to the amount of time they spend in the store, and even the dinkiest Barnes and Nobles superstore in Iowa City rakes in hundreds of dollars a minute while the independent booksellers are going out of business. The mature approach to strategy is not to try to force things on potential customers. If somebody isn't even your customer yet, trying to lock them in just isn't a good idea. Until then, if you try to lock them in now, it's too early, and if any customer catches you in the act, you'll just wind up locking them out .
Nobody wants to switch to a product that is going to eliminate their freedom in the future.
Something that virtually no ISP offers is the ability to get your email forwarded to another email address after you quit their service . This is small-minded thinking of the worst sort, and I'm pretty surprised nobody has figured it out. So they won't even want to try your service. If they do try it, they won't tell their friends the new address for a while, just in case it doesn't work out. Which means they won't be getting much email at the new address, which means they won't really be trying out the service and seeing how much better they like it.