I would suspect that OP is choosing the webpage out of convenience but that there is a List-Unsubscribe: header hiding in the raw version of the email, cheerfully nuking the FTC complaint. Now, demonstrating that the List-Unsubscribe worked is left as an exercise to the reader, but let's be honest, it's the same with the web page variant with bonus points for those pages usually ending it "yeah, we'll get around to it is 364 business days" or some shit