I’ve been running mailcow for almost 2 years with no issues. I’m not doing anything major with it, mainly using it to send myself alerts on the environment, but it does work for external purposes if I want it to as well. Updating is easy and seamless. I did get greylisted almost immediately though, so I use SMTP2Go and it works great as a free relay for the amount of mail I generate.
After I kbin.socials constant issues I moved to Leemy.world and like it a lot better. I miss magazines as opposed to communities, but it’s pot-ato po-tato and there don’t seem to be any outages.