I can understand you are one of the hacker group, or you bought these emails from the black market. Because you make sure emails are from crypto exchanges as well. It means it's from a data breach; either you connected with that data breach or you bought it. But what are the benefits exactly when you send them mail? I don't feel they would bother to click on the mail; at least I don't often click and mark them as spam. So it would just be a waste of money. On the other hand, we can't make sure whether these are crypto mail or not.

Unless they are your subscriber, then it will give zero results. A long time ago, one of my clients used that kind of service, but they didn't get any return. Once upon a time, crypto leads were available on the market for sale. But for now, I don't feel any demand for crypto leads. Those sites have their own subscribers, so an email campaign would work sometimes but doesn't guarantee anything. It's better to avoid such service in my opinion.