This is why a legit newsletter might have a confirm step:

https://news.ycombinator.com/item?id=27469535

I’ve had to deal with customers angry they did not get emails they wanted, and we tracked it back to a security service at their employer that auto-clicks all email links to check them. We had to add a confirm step to unsubscribe to keep it from happening. We’re B2B and I suspect it’s a much bigger issue than B2C because so many companies run custom email setups.