I agree with everyone here that self-hosting email is never easy, but if you still decide to go down this route then here are two tips that I personally found very helpful, especially when you decide to host it at home:

The first is to get an SMTP relay server. That’s just another mail server that yours can log into to actually send its mail, just like an email client would. That way you don’t have to worry about your IP’s sending reputation, because everyone will only see the relay’s reputable IP.

Second is to configure a Backup MX. That’s an additional MX DNS entry with lower priority than the primary, and it points to a special mail server that accepts any mail for you and tries to deliver it to the primary server forever (or something like an entire week). So when your primary server is unreachable other sending servers will deliver mail to the backup, and it delivers the mail to the primary as soon as that’s back online.

You can get these as separate services, but some DNS providers (like Strato for example) offer both with the base domain package. It makes self-hosting an email server much simpler and more reliable in my experience.