The username of your account to authenticate to KlickTipp.
The password of your account to authenticate to KlickTipp.
The email address of the subscriber you want to unsubscribe within KlickTipp.
(String) Register a custom WordPress hook callback. The value will be called as followed: do_action( $yourdefinedaction, $action_return_data, $request_data )
More available KlickTipp endpoints
To learn more about a specific endpoint, simply click on it.