Systers uses a custom version of Mailman that includes the ability to subscribe and unsubscribe to conversations.
If you would like more information about any of our community developed, on-going, open-sourced software projects, please join systers-dev.
Our source code is located on Launchpad
You can find us on irc at irc.freenode.net #systers-dev
Systers Google Summer of Code - 2009 Summer of Code Documentation including Project Plans
How to submit a bug to the Mailman project
Workplan for Mailman 2 and 3 patches
UI design documents - working notes for interface design