That's a whole lot of "what ifs". I'd rather just block people that are consuming resources and potentially affecting service levels for actual customers (or people that will actually convert). The situation you paint might be true of a very small percentage. But more often than not it's just people that want to use something without paying for it.
So don't let people use your services without paying! A trial is only a trial if it locks or stops the user from using it after a trial period. Freemium models that limits number of uses aren't a trial.
The trial does stop the user from using it after a trial period. If you want to fault anything, it's using an email address to equate to a user. Fine. I'm guilty as charged. But, it's pretty common. Most legitimate users of a service want as frictionless a setup as possible.
Ultimately, my solution was to start requiring a credit card at sign-up. Shockingly, not a single mailinator.com address was used from that point forward and my conversion rate barely changed. But, it sucks I had to do that. There were people that legitimately wanted to try the service out that were put off by requiring a credit card so early. I personally hate providing a credit card for a service I haven't even tried yet.
I appreciate your reply, but I think it's an entirely toxic mentality. My business model isn't freemium because you could game the trial process (and violate the terms of service). And I shouldn't have to grossly restrict the trial to deal with mailinator.com sign-ups. Say what you will about mailinator.com, but it was hands-down the largest source of abuse of my CI-like service. Everyone else played by the rules and enjoyed a liberal trial to get familiar with product.
