NOTE In ListManager 10.2b and later, this section is called Mailstream Queue.
The Sending Backlog Drilldown page shows you a breakdown of the information from the MailStream Blockage graph on the Deliverability Dashboard.
How to get there:
In the Sending Backlog section of the Deliverability Dashbord, click view data.
Column Descriptions
MailStream: The name of the MailStream.
Total: The total number of pending recipients.