Found it.
I’m redirecting all DNS requests from LAN to the opnsense. As I already wrote, on the opnsense UNBOUND is running. I have to think about creating seperate rules for the mailcow, or leave the workaround with the forward-zone.
Question remains why did it work in version 2024-07 (obviously because of changing the healthcheck script), and what reason for is DNS working inside of the unbound-container working with ping, dig and nslookup. Why in general, changing the script? Running mailcow behind a proper configured firewall will cause hickups.
I’ll stop this now. Maybe someone can mark this thread as solved or tell me, how to do it.
BTW - did I overlook something in the doku? Can’t find anything about this special? issue. Is it special to redirect any DNS request from a LAN to a firewall and let the firewall do the job? AFAIK there are reasons to configure a FW in this way…
