I have written an application, dkim-verify, that can be used to provide
DKIM verification in two situations that are not addressed in the standard
MTA + dkim-milter installation. Once case is verification of e-mail that
is locally originated and locally delivered (only signing is performed in
this case) and verification of mail sent by mailing-list software
(locally-originated and delivered mail from mailing list software may be
signed twice and not verified at all).
The application I've written is available on http://dkim.lotspeich.org/.
The README there gives more insight into the purpose and use of this
application. The software is quite "rough around the edges" and is very
raw. But this version is just a start and I intend to keep developing and
maturing the code.
Thanks again to Murray and SM who patiently answered my many questions and
helped me to understand DKIM and dkim-milter's libdkim library.
Questions, comments, and critiques are welcome...