Doesn't this just further the point that your potential customers don't want to identify themselves to try your product? Punting on anti-sybil or anti-spam by requiring a strongly identity-linked account (Google accounts can't be created from VPNs or without phone numbers, for instance) is user-hostile.
If your free users are using up paid user resources, that's a different problem.
One of the nice parts about starting a business is that you get to choose your customers. There is no ethical or moral rule that you must provide access to everyone who wants to use your app. You are even allowed to make decisions that reduce your revenue in favor of other priorities.
The problem is not that I want peoples real information, I really couldn't care less. It's the fact that some of these are clearly the same people creating hundreds of emails to just keep resubscribing to a free trial.
I could tell because there were emails with the sequence of:
If your free users are using up paid user resources, that's a different problem.