This allows the message displayed to a newly unsubscribing user that is displayed (after clicking the confirmation link in their email) to be customised.
function unsubscribe_change($message) { // default message is 'You have successfully unsubscribed!' $message .='I'm sorry to see you leave and I hope you found the emails useful.' return $message;}add_filter('s2_unsubscribe_confirmed', 'unsubscribe_change');