But also, those three are by far not the only ones, there are quite a few more significant email providers across the globe.

And also, there are tons of participants who use none of those services. Apart from some individuals running their own servers, lots and lots of companies run their own email infrastructure.

> Having an easy to use and safe federated system is discovering-the-theory-of-relativity hard, in my opinion.

The important thing is that it's way easier than a safe centralized system.