Pesquisa de soluções similares usando [procmail](http://www.procmail.org):
+ * [openpgpkey-milter](https://github.com/letoams/openpgpkey-milter).
* [mail-gnupg-encrypt.pl](http://opensource.platon.sk/cvs/cvs.php/scripts/perl/mail-gnupg/).
* [How to automatically PGP/MIME encrypt incoming mail via procmail](http://www.j3e.de/pgp-mime-encrypt-in-procmail.html).
* [Encrypted system logs to gmail using logcheck/procmail/gpg](http://blog.fealdia.org/2008/06/14/encrypted-system-logs-to-gmail/).