mail for virtual servers

Consult one of the many guides at howtoforge.com.

Is postfix up and running? You can check by clicking on "System Information" it's available either in Webmin or Virtualmin just above the "Logout" link. Open up the "Status" section and the "Postfix Mail Server" status should be present, you can start, stop and restart postfix from here.

You may also want to check if Postfix is configured to restart automatically on every (re)boot of your server. You can check that from Webmin > System > Boot and Shutdown. Here you can configure postfix or any other daemon's available to start automatically upon a reboot.

To receive and send mail after postfix is running you have to your domain and users set up, this you can do so in Virtualmin i.e. "Create Virtual Server" followed by "Edit Mail and FTP Users"

There's quite a bit of Webmin-focused documentation for Postfix in the Webmin documentation here:

http://doxfer.com/Webmin/PostfixConfiguration

And here:

http://doxfer.com/Webmin/PostfixBasicConfiguration

And here:

http://doxfer.com/Webmin/PostfixBasicConfiguration

Or, if you're using a platform that is close to one we support, you could just install the right packages (including Webmin and Virtualmin and Usermin) and run our mail-setup.pl script from here:

http://software.virtualmin.com/lib/mail-setup.pl

If you're using a supported platform, you should instead just run our install script, and it'll take care of everything.