@codingquark I used to have a good guide for setting that up bookmarked but I can't seem to find that anymore. It was a lot of initial setup (but still doable in an evening) the few times that I've done that, but postfix/dovecot will do what you want and doesn't require a lot of resources so it can piggy back on the same VM as something else if you've already got a server that's not at full load.
The main challenge is that the server software has tons of options you don't need.
@acidburn Yes it is, and I have about 1000 pounds of it on a truck somewhere.
The closer I get to finishing up my coffee roasting book the more I'm glad that this is going to be a thing that exists. I spent a lot of time hoping someone else would write it so I could just recommend that instead of needing to do the work myself, but there are a few books for the coffee industry that ought to exist that don't seem to and nobody qualified seems to be working on them (I know at least half a dozen people who should write roasting books and only one of them has).
Author of Typica software for coffee roasters.