Webmin 1.932 Virtualmin 6.08 Centos 7 Server example.com
I deleted a server: example.com. Some days later I had a reason to reboot the server. After the reboot Dovecot failed to start.
/etc/dovecot/dovecot.conf was looking for the ssl cert and key for the deleted server (example.com) and couldn't find it.
I edited dovecot.conf to manually remove the deleted server's entry, below, restarted dovecot and things were fine.
local_name example.com { ssl_cert = </home/example/ssl.cert ssl_key = </home/example/ssl.key }
Apparently Virtualmin does not delete the sever entry in dovecot.conf and that causes the failure upon rebooting.