The nbListServer is mailinglist daemon, which can be used with any mail daemon. It provides an Interface to easily integrate the management of the mailinglist(s) to a website.
MMReencrypt is an add-on for Mailman. It allows reencrypting mailing lists for added security. Users post messages PGP- or GPG-encrypted to the list's public key. MMReencrypt decrypts them, then re-encrypts the message to each subscriber.