Yahoo provides a feedback page where you can (and should) give them a piece of your mind. This is what I wrote to them:
But it gets worse. You signed us all up to receive paper junk mail, and even TELEMARKETING. For this, I pray for you all.
I don't pray that you receive some kind of divine enligtenment, and mend your ways. No, we're long, long past that. I pray that every last one of you contracts some horrible, slow-acting, flesh-eating bacteria which releases psychotropic toxins into your bloodstream that both compel you to watch reruns of "Thirtysomething" and give you explosive diarrhea.
If the Almighty is unwilling to grant you that on my behalf (this *is* Easter weekend, after all) I pray that He will at least see to it that you are all hit by a bus. Because you are all now, officially, Very Bad People."
They won't start sending spam for 60 days, so you have that long to opt back out of all this shit.
Man, I thought Yahoo was bad when they bought out eGroups and fucked over my friends who worked there by either laying them off, giving them lowball offers to stay on, or changing their jobs and responsibilities to something shitty...