To get all subscribers of an email list you can use the emailList you can call subscribers on an email list.
$subscribers = $emailList->subscribers; // returns all subscribers
To get the email address of a subscriber call email on a subscriber.
$email = $subscribers->first()->email;
Calling subscribers on an email list will only return subscribers that have a subscription with a subscribed status. Subscribers that have unsubscribed or are still unconfirmed (when using double opt in) will not be returned.
To return all subscribers, including all unconfirmed and unsubscribed ones, use allSubscribers.
If double opt-in is enabled on a list, then subscribeTo won't result in an immediate subscription. Instead, the user must first confirm, by clicking a link in a mail, before their subscription to the new list is completed.
To immediately confirm someone, and skipping sending the confirmation mail, use subscribeSkippingConfirmation: