Small but Effective Idea to Reduce Number of Unsubscribers
When I clicked the link to opt out, it took me to a landing page to confirm, but there was also an option to reduce the number of emails your receive to simply one a week. I can handle a weekly offer, so I chose that instead of flat out unsubscribing.
By offering an alternative instead of simply saying 'sorry to see you go', they've saved their list from shrinking by one - and probably many many more.
Just a thought.