webmail doesn't work

Fresh install - centos 6.3
installed a virtual server.
redirect the dns to the server’s address.
the site works,
but the webmail doesn’t work:

there is a redirection from webmail.monitoril.com to https://monitoril.com:20000/

but then I get:

Unable to connect

      Firefox can't establish a connection to the server at monitoril.com:20000.

Where should I start looking ?


Restarted usermin and it started working.