In fairness, things like postfix usually ship with very poor (not to say “moronic”) defaults. Like, postfix won’t even try to connect to tls-enabled smtp for outgoing email by default, and you have to explicitly point it at the certificate bundle it’s supposed to consider valid. And you have to tell explicitly to reject incoming plaintext connections from the public internet. And quite a bit more… Like, why doesn’t p…
Things like Maddy (https://maddy.email/) aim to simplify all this. Really great potential, but they're still work in progress.