Let’s say the recipient is considering unsubscribing. He or she may be too busy to search through the email to find the unsubscribe link, so he or she just clicks “Report as SPAM” to stop the emails from coming. This is the last thing any marketer wants to see happen. It negatively impacts sender reputation, requiring extra work to improve email deliverability. With the list-unsubscribe header, you will avoid getting into this kind of trouble in the first place.