Yep..! Guess I know that unsubscribed mail doesn't actually go to /dev/null like I heard it might.
The end result was commit 81a63729473baaf00c2548d8929b9388053aea05 sans the test from http://thread.gmane.org/gmane.emacs.orgmode/99888 after a little bit of "patch bootcamp" for someone who read README_contribute and didn't see the relevant section on Worg.
That said, thanks for the review Nicolas--I'll keep it in mind if I send another patch sometime.