This might be of interest to the Mailman User Community.

Our team has recently released SELS v0.4 software. http://sels.ncsa.uiuc.edu/

This software release has two parts. One for the List Server (LS), which enables a list administrator to set up a Secure List Server using Mailman and GnuPG. The second is for a List Moderator(LM), who uses this software to set up a secure list at the Secure List Server. Then any list subscriber can exchange emails with the other list members using COTS email clients with GnuPG plugins, ex: Thunderbird with Enigmail. One main feature of our implementation is that the contents of the email are never visible in plain text at the List Server. So even if the List Server gets compromised, the message contents remain encrypted.

We look forward to your feedback, comments , suggestions.

Thanks and regards Meenal Pant (SELS Team Member)