$ sudo apt-get update
$ sudo apt-get install gforge-lists-mailman 

gforge-lists-mailman is installed in your system.

Make ensure the gforge-lists-mailman package were installed using the commands given below,

$ sudo dpkg-query -l | grep gforge-lists-mailman *

You will get with gforge-lists-mailman package name, version, architecture and description in a table

gforge-lists-mailman package basic information: