There's alot that goes into a mail server stack, but it's no more complicated than k8s or other stacks these days. My preferred setup is rspamd/postfix/dovecot/roundcube. The docs are good and the mailing lists are active & archived for easy searching

For a pre-packaged mailserver environment, take a look at mailcow or mailinabox

https://mailcow.email

https://mailinabox.email/

There's a variety of ansible/chef/puppet up on github that can also be used to setup the invididual component

I've found that Mailinabox provides a pretty much turn-key setup. (https://www.mailinabox.email)

I've been self hosting my own email on a Dell Poweredge for just over a year now, if you want my smtpd, dovecot, and rspamd confs I'll share them :x

I haven’t followed any such guide, so I wouldn’t know, but there are usually lots of links in all these threads to such things.