docker run --name [--net=] -tid -p 20-21:20-21 -p 25:25 -p 80:80 -p 110:110 -p 143:143 -p 10000:10000 -p 20000:20000 giodegas/virtualmin-c7
Docker attach <name>
"sh install.sh -f"
and then enter a fully qualified hostname (for example, host.example.com) of the virtualmin host, that has to be resolved by DNS.