I have my own domain, and run exim+dovecot on a low spec Linux machine. This setup has run solidly for years. I serve E-mail for family and friends. When I first set it up, I had some deliverability problems, but once I had DKIM and SPF set up, it's been rock solid. No experience with containers or docker or any of that stuff, sorry.
My emails get rejected from @comcast.net but nobody else as far as I can tell. I haven't figured out a good way to debug the issue. As a result, I am not completely off of free Gmail. If you need your emails to be 100% received on the other end, I would recommend paying a hosting provider.
I would think there is some docker container I can run in a VM and go about my business.