It’s admirable that most email mailing list providers offer a double-opt-in system. That’s when you go to a web site, click on a link to subscribe to a mailing list and then you receive an email (the double part) verifying that you actually want to be subscribed.
Why is it that 80%+ of the email systems don’t have a double-opt-out system? The vast majority of the time, it’s even more shallow that. You click on a link in an email and it jumps to a page that reads simply, “You have been unsubscribed.”
Duh. What if I clicked on the link accidentally? What if I don’t want to unsubscribe but change my subscription? When I ran a large list, fully 10% of the requests I processed were address change requests. It is often a real pain to find the link to subscribe… such a pain that it’s not worth doing.