> The originating system generates e-mail and adds special headers
 > with a copy of the sender's public key and a cryptographic header
 > (encoded with the sender's private key and the public key for the
 > list and based on parts of the message). The receiving system passes
 > the email through a filter that checks for the special header and
 > matches it against the proper parts of the message using the private
 > key for the list and the public key from the sender. If it fails,
 > the message is silently dropped.  If it clears, the filter removes
 > the special headers and passes it off to LISTSERV.
 >
 > PK is a great idea, but it would be tremendously difficult to do
 > with a large list and a variety of people contributing. It's much
 > more easily done when you have something like an announce list.

Doug:

Interesting.  Hadn't thought of that approach.  I can see how such a
thing could be implemented in nearly any mailer, based on standard
tools.  It should even work for essentially public larger lists if
the subscribers could learn to fly their signing mailers.

I don't think it would work for us.  We're running mostly edited
lists, so subscribers need to be able to send posts without PK
signatures which LISTSERV will forward to the editors.  The editors
need to be able to send signed posts which get distributed.  I would
have to build an outboard implementation of a substantial portion of
LISTSERV's functionality in order to hack this onto the side.

Dennis Boone
H-Net