To retrieve all subscribers from a mailing list, you use the NewslettersManager class. First, you initialize the NewslettersManager. Then, to retrieve all mailing lists and filter them based on the Id property, you must call GetMailingLists. You check whether a mailing list with the specified ID exists. Finally, you get all subscribers from the mailing list and return them as a result.
The following code retrieves all subscribers from a mailing list with the specified Id with the Native API: