Mailman currently runs only on GNU/Linux and any other *nix-like operating system, such as *BSD, Solaris, etc. It works on MacOS X but not on MacOS 9. It probably does not work on Windows, although it's possible you could get it running on a Cygwin system (please let the developer community know if you have success with this!)

You must have the Python interpreter installed somewhere on your system. Currently (as of 2010-04-14) Python 2.4 or newer is required, with Python 2.6 being recommended. Mailman is not yet compatible with Python 3.

Most GNU/Linux systems and MacOSX come with Python pre-installed, so you just need to make sure you're running an up-to-date version. You can do this by executing the following at your shell's command line:

% python -V
Python 2.6.5
If your Python executable doesn't understand the -V option, it's definitely too old!

You must have a mail server (MTA) that you can send messages to, and a web server that supports the CGI/1.1 API. Apache makes a fine choice for web server, and MTAs such as Postfix, Exim, Sendmail, and qmail should work just fine.

You will need an ANSI C compiler to build Mailman's security wrappers. All modern versions of the GNU C compiler should work well.