Dovecot + postfix + spamassassin for mail. radicale for CalDAV/CardDAV (calendar and contacts). Squirrelmail for webmail used to be ok (though I haven't used it in a long time).

Or there's an embarrassment of riches out there if you prefer to pay someone for a nice web-based zero-management thing. I can't really recommend one, but I was reselling a whitelabel email service with pretty reasonable capacity and featureset to a bunch of businesses for $5/month/user about 5 years ago. A couple of people I know seem to like protonmail.

Some ISPs might even still provide email. Though that leads to a vendor-lock-in problem and you're better paying for something distinct from your ISP IMO. Same goes for the addresses Apple hands out "free" to their users.

The main trick is to remember the old adage: "If you're not paying for it, you are the product" - If you don't want to pay for email then you might as well just stick with google.