If you aren't sure who is subscribed to your list(s), as a list owner you can review a list's configuration and the addresses of its current subscribers with the following email command:

review listname

"Listname" is the name of your list (the text before the "@" of the list address).

If the list configuration is incorrect or needs changes made (e.g., a new list owner or authorized sender needs to be added), contact the Mass Mailing team.