Unfortunately, it performed very poorly on emails. The hit rate was
low, and when it did it, it was on email that already scored in the
14+ points range. I had high hopes for the lists, but it turns out
not to have worked the way I wanted it to. I developed the code on my
own time, and then ran it at work, so I can probably provide the code
if you're interested. Said code is pretty rough, but it did work.
But to answer your question, it does appear (by my reading of the
agreement) that you'd have to make everyone get their own key, and put
it in some config file somewhere.