Well, I wish my ISP would stop marking ads and promotions as "transactional". Just because they have a system that prohibits unsubscribing, doesn't mean they should be allowed to abuse that system.
I've had a website that sent me no fewer than 6 emails over the course of 10 days for a single transaction, 5 of which were full of ads and links to their website and products. I emailed them and asked them to stop and their response was there was no way to opt out, they were transactional for new accounts.
My ISP constantly sends me emails about "staying safe online" and "the holiday season". At the bottom of the email, it says "THIS IS A SERVICE-RELATED EMAIL", supposedly to excuse the lack of any unsubscribe link.
Unfortunately you are no longer allowed to take them to court over this, as their terms of service simply say you are no longer allowed to sue them :) just like all tech companies that know they're committing lawsuit-worthy offenses.