Insanity
I've been registered as a non-partisan/decline to state voter since the day after I turned 18.
I've heavily considered Libertarian, Green, and Independent status, and given slight consideration to the Democrats.
I recently became a card-carrying member of the ACLU. I also support Doctors Without Borders, the EFF and a few other progressive organizations.
I regularly write letters to my Senators, both of whom are Democrats (in title, at least.)
So I guess it was just a matter of time before I got a mailing from the DNC.