e.g: https://mailinabox.email/ (from a quick 5 minute google).
All in all, it worked fine. Might still be doing it except that I decided to run it on CentOS 6, and when it became necessary to migrate it all to CentOS 7, that seemed like it was going to be a lot of work, since there was no very good way to do an in-place upgrade.
Had I chosen FreeBSD to start with, I might well still be running it, since major-version upgrades are so straightforward. I chose linux at the time partly because I wanted to learn more about it.
In the end, I migrated to Fastmail and have never once thought, gee I wish I was still running my own mail server.
Also worth noting that with my two-year plan, Fastmail is cheaper. Not a lot, but I think it's worth pointing out that running your own mail server will probably not save you any money in the long run, so that's not a good reason to do it.
I ran one for years, Sendmail at first, switched to Postfix, but I was eventually overwhelmed by spam in 2018.