E-mail was the first "thing" that got me off of Google (to Proton & then currently Tutanota) but is really the last remaining service I not have self hosted.
I have always read about how difficult and time consuimg it was to run your own mail server, but I felt like I needed to experience it myself. So I purchased another domain and followed the instructions on https://mailinabox.email/.
I am using a small VPS on Hetzner and I have to say the experience has been almost flawless so far. I did need to have my new domain taken off the Domain Block List, but Hetzner gave me a clean IP and defaults to blocking port 25 outbound to prevent spam (simple ticket to open, once account is 30 days old and paid).
I know I'm still early into this journey so far, but it has been really simple and I plan to test this secondary domain for a few months before moving onto it full time.
As an avid self hosted of literally everything else, I can say it has been a lot of fun learning so far!