Renders a subscription form for registered users only. If you want anyone to be able to subscribe, this is not what you want to use. Use the [groups_newsletters_subscribe] shortcode instead.
Attributes:
description: Text used to invite to subscribe, defaults to ‘Subscribe to our newsletters’.description_class: CSS class applied, default: ‘description’.subscribe_label:Label used for the Subscribe button, default: ‘Subscribe’.subscribe_class:CSS class used for the Subscribe button, default: ‘button wp-element-button’.user_confirm_message: Message confirming subscription, default: ‘Thank you. Your subscription is confirmed.’.user_unsubscribed_message: Message after unsubscribing, default: ‘Thank you. Your subscription has been removed.’.log_in_message: Ask visitor to log in to subscribe, default: ‘Please log in to subscribe.’.show_log_in_message: Whether to show the message, defaults to ‘yes’.show_unsubscribe: Whether to show the unsubscribe option for subscribed users, defaults to ‘yes’.unsubscribe_label:Label used for the Unsubscribe button, default: ‘Unsubscribe’.unsubscribe_class:CSS class used for the Unsubscribe button, default: ‘button wp-element-button’.subscriber_message:Shown to subscribed users. Default: You are subscribed to our newsletters.’.subscriber_class:CSS class used for the subscriber_message, default: ‘subscribed’.