If you're using Mailman, you should be aware of several moderately critical vulnerabilities that have been discovered: mailman - Multiple Vulnerabilities. Please note that the only newer version of Mailman available is a release candidate so I don't recommend upgrading yet. Once Mailman 2.1.9 is out, please feel free to file a ticket and we'll upgrade any existing Mailman instances for you.

Update: Mailman 2.1.9 is now out. If you're using a previous version, please file a ticket to have us upgrade your Mailman install.