I does a firs installation of virtualmin; when I click on Virtualmin Virtual Servers > Refresh configuration I have this error A problem was found with your Postfix virtual maps : No map sources were found in the Postfix configuration
In Server>Postfix Mail Server>Virtual Domains I have Domain mapping lookup tables - Map specifications this values: proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, proxy:mysql:/etc/postfix/mysql-virtual_email2email.cf, hash:/var/lib/mailman/data/virtual-mailman
While in Server>Postfix Mail Server>General Options I noticed this in What domain to use in outbound mail : 1 Use hostname 2 Use domainname 3 is checked this radio and have this text $myhostname/usr/sbin/postconf: warning: /etc/postfix/master.cf: unused parameter: smtpd_bind_address=127.0.0.1
during installation I add at dns list also 127.0.0.1 because pc server I use at home for test and haven't a domain ( how domain I set this example.xxxx) and virtualmin noticed me that was necessary to setupa a dns zone for itself