Add contact records that have already been created in the system to a contact list. You can add multiple records at once, either by vid or by email address. Up to 500 records can be added to a list in a single request, including records specified by ID and by email.

Please note that you cannot manually add contacts to dynamic lists. To determine whether a list is dynamic or static, when you get a list, you will see a flag called dynamic that equates to true or false.