Lancelot is a flexible mailing list manager with a modular architecture that allows for customized configurations.
As a work in progress, Project Lancelot still has a ways to go before it's ready for use in serious applications. However, the latest release does come with a notable new feature: automated bounce processing via VERP.
All in all, if you need a straightforward mailing list tool that you can customize to your liking, Project Lancelot is worth checking out. Just be aware that it's not quite ready for prime time yet.
Version 0.2: N/A