Consider only making lists private that are used for internal purposes only. When recipients try to unsubscribe from a private list by clicking the unsubscribe link, they will only see public lists and cannot unsubscribe from individual private lists. The only way recipients are unsubscribed from private lists are when they unsubscribe from all communication (global unsubscribe).
Test Lists can contain no more than 20 Prospects.
Test lists can be used to get feedback from recipients, such as your internal team. Test lists cannot have more than 20 recipients per list. To create a test list do the following: