Selfhosted

I guess slapping it on my local raspberry pi wouldn’t be enough no?

Oh no, that would be way not enough. :) Managing a mailserver is a sysadmin task by itself. While you don't need to do much once it works (which often is a perk of sysadmin work, compensating for the fact that when it does not work, they may have to wake in the middle of the night to fix it), it's notoriously difficult to get right : you have the configuration of the mailserver to get right first, so that you can send emails, but nobody else can and you don't become a spam relay without knowing it. Then you have a lot of configuration to do to be able to retrieve your emails from your server, which uses other protocols that you must learn about. Then you have "optional" things that you must setup (SPF, DKIM and DMARC), which you won't be able to send mails to gmail or outlook if you don't set them up properly. And when you will have got all of that right, you will have enough experience to be hired as a sysadmin. :)

I can't provide a good resource for learning it, I learned it 15 years ago when it was way more simple (before SPF and DKIM), and picked every addition as they appeared, but any course on how to manage a mail system will do. There is no difference in doing it for your self-hosted server and for a company (except maybe that for a company, they'll make you handle users in a database, which you can forego for your own needs). I would recommend to learn how to use postfix first, then any imap server (courier-imap is a top runner), and when you're comfortable with that, you can learn about SPF, then DKIM, then DMARC. But be aware before going through it that this is basically learning a new skill (sysadmin). You can find docker images that setup everything automatically for you, but I would recommend against that, because at some point, things will break and you will have no idea how to fix them. And if you try to fix them while not knowing well what you're doing, that's a good way to end up being a spam relay. Plus, those docker images are difficult to customize, which quite defeats the point of managing your own mail system to begin with.