Messages seems not not reach the recipient's mailbox

Hi again,

Trying to figure this out. In Ubuntu, I can configure DNS via bind9 (bind zones), however, I’m not seeing anything familiar. I’ve already configured /etc/resolve.conf and /etc/hosts. Do I need bind9 for it?

How do I configure NS to recognize my 3 domains (nethdomain, nethdomain.local and testdomain.local)? It’s already in Configuration > Email | Domain.