Do you mean buying your own domain, and forward email sent to it to an email provider?

A lot of email providers have that option (with paid plans). For example

https://proton.me/support/custom-domain

I use Mailcow myself and as long as you follow all the necessary anti-spam steps (DKIM/DMARC/SPF/etc.), it seems to work just fine.

If you're not into all that, I would definitely recommend Proton's hosted option. Other hosted options are also just fine for most people (even Google and Microsoft will provide you with affordable and reliable email hosting) but those are generally run by Big Tech™. On the other hand, supporting the little guy is nice and all but it also leaves you open to hacks and business continuity risks if the hosting market ever takes a turn for the worse.

@WandererLagomorph799 There are many providers who allow you to bring your own domain. The ones I know of are Disroot, mailbox.org and skiff.com. The main advantage of using your own domain is also that if you ever want to change your email provider, you can do so without changing your email address. So even if you choose the wrong provider at first, it's not really a problem.

Assuming that you do want to fully self host, my go-to is a postfix+mariadb+postfixadmin+spamassassin+opendkim stack. With rainloop as a webmail if required.

Avoid exim like the plague