Tell us when an Open-link unsubscribe did not work

When you press Open link, the row turns green straight away. The link sometimes lands on a login wall, a preference centre or a 404, and today there is no way to tell us it did not work. We would add a small “Did it work? Yes / Didn’t work” prompt on the row, so a failed link is recorded honestly and the sender gets the block option instead of a false tick.