Well all AI will find is government shit and get the latest discount on various items emails… maybe it can start making sense of all the government shit!
Like many others, I use Gmail even though I know they have access to and utilize all of my information. Unfortunately email is a special case where setting up your own private system is generally not worth it. You could consider a privacy focused alternate like ProtonMail, but there is a trade off. First of all you, you still have to trust them. Not only that, their reliability isn't going to be as good.
What I do is use them in a way I don't care if they see my data. So they can see my monthly bills or email verification when I login somewhere; whatever, I don't care. I don't use them for anything I'd have a problem with random people finding out.
Nowadays to use basic common technology requires giving up your privacy, and it can be hard to use alternatives. Your cellphone ios/android, msging with whatsapp, social media, chatGpt - everything really. It's really a shame technology went this way.
There are some things you can do like run your own (inferior, but decent) AI, use a privacy phone or apps, signal for msging, or build your own private cloud (nextcloud and others). And I personally do some of this where I can. But good luck convincing your old parents or family to use something like Signal over whatsapp.
Notes from setting up a truly minimal self-hosted email server with Postfix and OpenDKIM. Covers TLS, SPF, DKIM, DMARC, DNS, reverse DNS, multiple domains, and delivering to Gmail.