Had been running my own mail server for the last 10 years, doing mail forwarding for a few friends domain names. Finally just moved all those domains to mailgun, and it's been great. 10,000 forwarded emails a day, for free.

To be honest it wasn't that hard doing it myself, but it broke 2-3 times over that number of years when providers changed their delivery requirements (see DKIM, DMARC etc). It was never something I enjoyed troubleshooting.