As noted in the Glossary, a List is
Managing a Recipient List
There are three recipient tabs on the main admin console for better management: Email, SMS and All. From each of these sections, functions can be performed based on one of three recipient statuses: Subscribed, Pending, or Unsubscribed.
The Subscribed status is defined as a recipient that has opted in to receive communication, either via email or SMS.
The Unsubscribed status is defined as a recipient that has opted out of receiving messages, either email or SMS.
The Pending status is defined for a recipient that has yet to confirm or opt-in to receiving SMS or email messages.
For example, to access Unsubscribed email recipients, go the Recipient tab > Email > Unsubscribed.