To configure a POP/IMAP server, the xinetd and imap-2000c packages must be installed.

The server configuration is done through the Extended Internet Service module. You can find this module in the Servers category. If you don't find it, you can get the file xinetd.wbm from the Webmin site and install it by using the Webmin configuration module of the Webmin category. If you click on the Webmin modules icon, you will end up on a page where you can tell Webmin the path to the module to be installed (or removed).