CPO is a tool written in Java that manages newsletters. It's focused on corporate needs (privacy, scalability, bounce count, opt-in & out, newsletter statistics).
Ichabod is an SMTP/POP3 server, with mailing list support. Administration is via a web, or email
You can also use Ichabod to make your app receive email as an SMTP server.
You can also easily extend it by subclassing to add your own behaviors.