Yii::app()->hooks->addAction('frontend_controller_lists_before_action', function(CAction $action){
$action->controller->callbacks->onSubscriberSaveError = function($event){
$instances = $event->params['instances'];
$subscriber = $event->params['subscriber'];
$list = $event->params['list'];
$action = $event->params['subscribe'];
if (EmailBlacklist::isBlacklisted($subscriber->email)) {
// is blacklisted, do something.
}
}
});