Sierra Club are spammers

All of a sudden, for some unknown reason, I have started getting e-mails and newsletters from the Sierra Club. I’m not a member, have not registered at their site, and when I try to unsubscribe it seems to go into a black hole. If anyone has any suggestions on how to get off their lists, please contact me. It’s not that I’m not interested in saving the planet and the environment, but I really don’t want to start getting e-mails from every environmental organization known to man. I suspect the culprit is Care2.com, where I did register many moons ago, and foolishly have responded to their calls for activism such as signing various petitions. I can only conclude they sell their e-mail lists far and wide. For awhile I was receiving spam from all kinds of groups, (League of Conservation Voters, some abortion rights group, and about 10 others I can’t recall now). I managed to get off all those mail lists, but the Sierra Club seems more pernicious than the rest. Seriously, how many of these things do they think one person can respond to? I pick my battles, and I did not pick them.