Not a single tutorial comes to mind but you generally find a wealth of resources and tutorials online about setting up anything you might need.

Always start by setting up a strict firewall and then whitelist cautiously anything you need as you set up the rest. Don't bother with SELinux. Be very careful with your Postfix (or if you're masochistic, sendmail) config as it's rather (needlessly IMHO) intricate and it's easy to end up with a configuration that appears to work but is extremely broken. In particular if you end up configuring an open relay by mistake spammers are going to have a lot of fun with your server but you'll end up blacklisted everywhere.

My "stack" is nginx for web, postfix + dovecot + spamassassin for email (+ roundcube when I wanted a webmail). Postfix was by far the trickiest to configure, although if you find a good tutorial online and can spare a couple of hours to understand how it all works it's not too bad.

I have similar setup but use Exim instead of Postfix. And I am still glad I host my own services. Yes, it took time but it will work as I want it forever. Only lazy people prefer ready-made cloud services - yes, it's convenient - but it's more costly, you lose control over your data and they are constantly redesigning and reinventing something. You never know when they sell the business or increase prices, ban or limit you.