This patch adds some basic instructions to the documentation on how to
set up DKIM, using the tools supported by the example hook.
It's not meant to be a full DKIM how-to, but to help someone who already
knows enough, or who is complementing it with a more general purpose
DKIM guide.
This patch adds support in the default hook for using dkimpy for DKIM
signing.
Unfortunately, dkimpy binaries have the same name as driusan/dkim's, so
we need to use --help to disambiguate. It's not pretty but it should
work, and is quite self contained.
Also, for the integration tests, we still need driusan/dkim because
dkimpy lacks the features needed. Specifically, dkimpy's dkimverify
can't be made to use custom DNS, or override the TXT values in any way,
so we can't verify that the generated signature is reasonable.
Thanks to ne9z@github for suggesting this change and providing an
alternative patch in https://github.com/albertito/chasquid/pull/19.
This patch adds DKIM signing using https://github.com/driusan/dkim tools
to the example hook.
It also adds an optional integration test to exercise signing and
verification, and corresponding documentation.
