If you’re looking for a nice and simple mail server and you’ve got some experience with Linux I can highly recommend Mailcow Dockerized.
Personally I’ve had it up and running for a couple of years now, with no downtime and no cost.
More here:
Mailcow Dockerized documentation
I find this to be very stable, it has support for the needed protocols and it is very versatile in terms of config options.
Also it being containerized makes it a breeze to keep updated thus more stable.
As an example it is kept up to date by the following two commands:
./update.sh
and the cleanup after verified success:
docker system prune
Mailcow uses well known add-ins for antispam, banning, filters etc. and it has some good logging capabilities and a nice web interface.
The community driven support is also good and the documentation is excellent.
Give it a mooh😂
