Mailing list + PGP/GPG support

Question

I would like to create such mailing list where every contributor must sign his/her messages with PGP/GPG, otherwise mailing list software would block unsigned message.

All PGP/GPG public keys of users allowed to post should be stored somewhere on mailing list server.

All other users are allowed to read mailing list in read-only access at the same time.

To what open-source mailing list software this feature can be easily added?

Answer 1

Pick whatever MTA and list manager you want. Install procmail, write quick procmail recipe to look for PGP signatures - allow message if the sig is found, deny if not found.