for me the problem is as simple as not allowing a third party to classify what i consider spam. i do that on my own. and what i classify as spam has no bearing on anyone elses classification and vice versa.

most critically however, i would like my email client to track which email i used to subscribe somewhere. which emails are replies to emails i sent out. which senders i approve of or are in my contact list (or are addresses i set email to before). these should be overriding any global classification as spam. subscription emails should be classified as such and not as spam either.