We subscribe emails to get notifications about promotion information and new product release alerts, while we unsubscribe emails for various reasons. However, they never ask why users leave and what's their preferences. As a result, users can no longer get email alerts for product updates, and Yamibuy.com lost the customer forever.
"I just wanted to receive emails once a month instead of everyday, I don't really mean to cancel the subscriptions."
As shown below, you can only see " You have successfully unsubscribed from Yamibuy emails." when you click the unsubscribe button.
My solution is divided into two parts. When users subscribe the email, get the preference in advance; When users unsubscribe, provide the choice to change the preference so that users can still stay.
As you can see below, this is the email page users would see when they subscribed the email. Except for a big welcome at the top, users can select what type of email they'd like to receive. In this case, we set an expectation in advance regarding what users will get. Thus, users are less likely to unsubscribe emails.
Instead of simply saying that you're unsubscribe successfully, users will get a chance to change the preference to give yamibuy.com a second chance. Sometimes, users just want to receive emails in a low frequency, not unsubscribe.
Problem solving skill can be practiced in everyday life. Try to make some improvements is better then simply saying it's a bad UX design.