I started hosting my own email in 2004 before finally giving up and migrating my email to Fastmail last year.

Besides the problems mentioned in this post the real problem I had was dealing with spam. The open source community around spam has really degraded over time, to the point where most solutions are extremely high maintenance and require regular tweaking. Methods that used to work, like greylisting, cause problems when dealing with GMail because google doesn't play nicely with it. The big spam blacklists have also gotten a bit less trustworthy over the years.