I was thinking primarily for close friends, but for broader contacts, I agree with you, so I was thinking of a system that would allow them to unsubscribe from certain topics (e.g. politics)
So if that person clicked link #1, the token in the link is verified that it was created for that email address, and then it's noted in a database. In the future, if person X sends another email for that category, it won't go to that person. I'm thinking the sender wouldn't even know that the person unsubscribed