Did you ever post to this list? Because a lot of lists have subscribers there who just randomly (and evilly) subscribe people to other lists that they think might be "useful". For example, there are some people who lurk on the Freecycle lists, and every time someone posts a "WANTED" mail, these people sign them up for "living frugally" or "being generous" mailing lists. Similarly, judging from occasional posts to yoga, I wouldn't be shocked if there are people out there who think anyone posting to a yoga list needs some more Jesus in their life and so just start signing them up for incoming Jesus.