Title: Previous Mailman Releases
Mailman 2.0.13 works with any Python version from 1.5.2 to 2.3 (still in alpha development as of this writing 26-Dec-2002). Mailman 2.1 requires at least Python 2.1.3 and works best with Python 2.3 or 2.4. If you plan on upgrading Mailman, I first recommend that you upgrade Python, and then upgrade Mailman.
There are tons of new features in Mailman 2.1, and no new development is being done on the Mailman 2.0.x branch.