Unless you are hosting your own server and don't store your mail on a third party in the cloud (but that is probably true for all your data that is hosted by a third party, not just email)
Yup. And exactly why the next president after that law was signed setup their own private email server in their home.
I have no idea why there weren't a million news stories about WHY you should setup your own private email server in your home and how to do it.
In fact a startup might find the perfect sales pitch to have a plug-and-play mail server for your home. $100 shipped to your door, plug it into your router and give it a domain name.
Gmail likely has most of your emails due to the fact that many people use it. See for example this analysis[0], where the author says that over 50% of his emails have transited on a Gmail-owned server.
That law is over a decade old.