[agwa]

If you're using procmail as your delivery agent, then adding this to your procmailrc should work:

  :0fw
  | /path/to/gpgit.pl [e-mail]

Be sure to also enable opportunistic transport-layer encryption in Postfix (it's pointless to encrypt mail upon receipt if it just traveled in the clear on the Internet) by putting this in main.cf:

  smtp_tls_security_level = may
  smtpd_tls_security_level = may
  smtpd_tls_cert_file = /path/to/cert
  smtpd_tls_key_file = /path/to/key

You need a SSL cert for this, but it can be a self-signed cert. If you're on Debian (probably Ubuntu too) you can use the snakeoil cert (/etc/ssl/certs/ssl-cert-snakeoil.pem and /etc/ssl/private/ssl-cert-snakeoil.key).

[nilved]

What if you aren't? :)

[agwa]

Aren't using procmail? You could try using a Postfix content filter:

http://www.postfix.org/FILTER_README.html

I've got no experience with them though.

[nilved]

Indeed. Thanks a lot for the link.