There's been more than once that someone asked here when I'd have multiple domain support available for dkimpy-milter. Now. I've released 1.2.0. It can be installed via pip or you can download the source from pypi or https:// launchpad.net/dkimpy-milter/1.2/1.2.0 .
I don't intend to make a habit of such announcements. Scott K