I often receive emails I never signed up for. My newsletter (which I haven't sent out for a year - but plan to!) and blog are double opt-in. That means you don't just tell me you want them once, you tell me twice. I never add anyone without permission and I couldn't if I tried.
Permission marketing is about permission. I might withdraw that permission, in which case I will opt out. But if I never gave permission, and the unsubscribe option isn't one-click, I feel no qualms about marking an email as spam.
I recently had an associate dump a heap of political vitriol on me. I never opted in to that conversation. I'm ready to unsubscribe. And if the opt-out isn't one-click, I might have to mark him as a spammer too. Metaphorically speaking.
Are you embroiled in any conversations you didn't opt in to? Why not unsubscribe now! Time is too precious to indulge the uninvited.