[berkes]

In this case it's both tracking and a legitimate feature: being able to place unsubscribe links in the "web version".

I'd argue that this feature is not worth the privacy invasion, but for it to work, you do need a secret in the URL that is always personal.

[sundvor]

They could easily have left the unsubscribe in the email, and linked to a UID of the mass mailout text instead for the web view.