The vast majority of "newsletters" I get today are from companies that assume that I want to keep hearing from them just because I once did a one-time transaction with them. And no, it's not because I forgot to uncheck the "I want to receive blah blah blah" checkbox. I'm careful to opt out whenever there's an option for that.
I don't know about other people, but I call that stuff spam. Just because it isn't an e-mail from someone who got my address from a dump and decided to cold-mail me with their crap (or phishing or other scams), doesn't mean it's not unsolicited e-mail, i.e. spam.
Maybe things have changed over the years and I just wasn't paying attention, but I've trained myself not to press "unsubscribe" on something I didn't explicitly opt in to receive.