I get a moderate amount of unsolicited e-mails from conservative organizations. For example, I just received an e-mail from Richard Viguerie. This is odd, as I am not, uhm in his target demographic (to put it mildly).
I'm pretty sure I know what happened. I once put a poll on my dailykos diary asking if people believed in efficiency wage models. There was almost unanimous agreement.
I wondered if this was a characteristic of lefties or generally agreed (among non economists -- the models are controversial to disreputable within the economics profession). So I set up an account at freerepublic username honestliberal. It's not that I think most liberals are dishonest. I was just stressing that I wasn't pretending to be one of them. I found that freerepublic diaries are moderated (given how moderate the stuff that get's through is this is shocking). I gave up.
I'm pretty sure that freerepublic.com sells e-mail lists. I can't think of another explanation. Well maybe they give them away.