Bob Tanner <tanner at real-time.com>  wrote:
> Anyone heard of a way to encrypt every sent message at the MTA level
> with a specific key?  I don't mean smtp with tls, I mean literally pgp
> encrypting and signing each message.

It's certainly possible, but you'd most likely need to script it
yourself.  You'll run into problems with what type of encryption scheme
to use, i.e. public key or simple password.  What exactly do you want to
do?  Do you want to encrypt only the body, or do you want to encrypt the
headers as well.  You can literally deliver a fully encrypted email to a
recipient based only on he envelope.

To do this automatically at the MTA level, you'll need to be able to
handle MIME attachments.  You may even want to automatically compress
the attachments, though you'd want to consider the encryption algorithm,
some of which do compression automatically.

A search[1] on Freshmeat[2] turned up the project "GNU Anubis"[3].  It's
not exactly MTA level, but I'm sure you could create a custom filter for
postfix, exim, or sendmail to handle the "pass through".

It looks like most tools concentrate on the MUA.  There's a dead project
out there called GEAM, but I didn't find any code associated with it.
Regardless, you'll be adding some sort of custom filter, and maybe
Anubis or Aegypten[4] are your starting points.

References
==========
1. http://freshmeat.net/search/?q=encryption+MTA&section=projects
2. http://freshmeat.net
3. http://www.gnu.org/software/anubis/
4. http://www.gnupg.org/aegypten/
-- 
Chad Walstrom <chewie at wookimus.net>           http://www.wookimus.net/
           assert(expired(knowledge)); /* core dump */

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