what software is the server running? Is it Open Source?
I am interested in it because I run a small site for my BioFarm in Estonia and use the Courier Mailing List Manager.
Just as a pointer, if you want to take a look at the code the main postgresql archives uses, you can find it at https://git.postgresql.org/gitweb/?p=pgarchives.git. Since it's postgres it's of course open source, and contributions are welcome!
I can't tell you how it differs from the one Jordan is posting, because if I go to that site I just get empty templates and it's failing to load the javascript properly from here. But I'm sure you've seen the archives, and can compare yourself! I'm sure it has good points to it, otherwise it wouldn't have been written :)