I self host it on my Synology NAS at home, using their MailPlus server and clients. It definitely took some time to get it up and running, but now it works without issue and very little maintenance required. My domain provider also acts as backup mx (for when the NAS is offline) and SMTP relay (for sending IP reputation), and the NAS does a daily encrypted cloud backup so nothing can be lost.

The one pain point I have is spam blocking. It does a good job blocking most of the spam, but it's not as good as something like Gmail unfortunately. I have to add custom keyword filters from time to time, and I still get 1-2 spam mails every day that make it past the spam filter. There are paid services to filter out spam, but I think it's not really worth it in my case.

Here is a breakdown of the costs I posted the other day. I'd pay for the NAS, domain and backup service anyway, so the email self hosting is basically free.