Having your own mail server could be useful but also sometimes dangereous. I am happy to see appliance such as iRedMail which cover variaty of topics regarding a somehow complete solution. I pick Ubuntu 22 on Hetzner. First you create DNS A record for your mail server and following by this a MX record pointing at that A record. Be sure to set proper hostname in the system. You can check it with: Ensure you have it set also in /etc/hosts and /etc/hostname. Next download iRedMail installer and iRedMail.sh script. It will prompt for various things but in my case