Yes, postfix+dovecot+sqlgrey+postfixadmin, since about two decades. Well I started out with qmail+vpopmail+courier way back - no one recommends that nowadays I'd wager!
My current setup is about 15 years old and takes very little effort to maintain.
Several domains, several aliases, but I'm intentionally the only user. Because if I would hand out aliases to people they'll inevitably start receiving some spam there, that then gets forwarded to the {hotmail, gmail, ...} that they're alased to, and when at those termini it can be subsequently marked as spam. I surmise that that could be bad for my mail server's reputation and that's why I don't hand out aliases. That's just caution. There's plenty signal for the top-10 mail hosters to tune their reputation heuristics to so that that wouldn't happen, but I don't trust that they worry enough to invest smarts in improving the general state of email delivery. The incentives are not there. They're the incumbents, and interoperable federated services were good news when they were starting up (whooo hey we bought Postini and now we're doing this web based office thing where you can send and receive email, come join us in the beta, free forever, promised!" aka GSuite), but now that they're incumbents it's better to stamp out those cooperative federated protocols. Before anyone gets any ideas that you could actually own your own data and and could communicate with people over the internet independently of some FAANG-size corp, you know.
Several domains, several aliases, but I'm intentionally the only user. Because if I would hand out aliases to people they'll inevitably start receiving some spam there, that then gets forwarded to the {hotmail, gmail, ...} that they're alased to, and when at those termini it can be subsequently marked as spam. I surmise that that could be bad for my mail server's reputation and that's why I don't hand out aliases. That's just caution. There's plenty signal for the top-10 mail hosters to tune their reputation heuristics to so that that wouldn't happen, but I don't trust that they worry enough to invest smarts in improving the general state of email delivery. The incentives are not there. They're the incumbents, and interoperable federated services were good news when they were starting up (whooo hey we bought Postini and now we're doing this web based office thing where you can send and receive email, come join us in the beta, free forever, promised!" aka GSuite), but now that they're incumbents it's better to stamp out those cooperative federated protocols. Before anyone gets any ideas that you could actually own your own data and and could communicate with people over the internet independently of some FAANG-size corp, you know.