The new features in Mailman 2.1 are extensive, but the most visible addition is the support for multiple natural languages. This means that all the administrative and publicly visible web pages, all the email notifications, and even the built-in archiver can be configured to produce text in any of nearly 20 natural languages out of the box. A large part of the re-architecting of Mailman for 2.1 has been to provide a framework for easily adding new natural languages as they become available from volunteer translation teams.