Mail Server set up

Hello @ilouie and welcome to the community.

We were very recently discussing a related issue and that might point you in the right direction.

Unlike CWP, Virtualmin does not configure pop3, smtp and imap sub-domains. For all protocols, mail.domain.tld does the trick if you are using the very latest version of Virtualmin and Postfix, else use mail.hostname.tld for incoming and outgoing server.