I've heard good things about Mail-in-a-Box[0], but haven't used it myself (although I have/do use(d) a bunch of the servers/tools amalgamated into the product).

The setup guide[1][2] also gives a good overview of implementation requirements.

Have fun!

[0] https://mailinabox.email/

[1] https://mailinabox.email/guide.html

[2] Annoyingly, the setup guide wants to you 'curl setup.sh | bash'. You might want to check it out first at https://github.com/mail-in-a-box/mailinabox

https://github.com/iredmail/iRedMail