That is a really good question! So, contacts can be imported without a list assigned, and if that is the case, you can do an advanced search look-up to find all contacts that have their List variable as "is blank." If you click on the Active tab on the left hand side of the screen, then the Advanced link under the search bar:
You can then do an Advanced search for "List" "is blank," and hit search:
This will pull up a list of all contacts who are not on any lists. Bear in mind, this does contain unsubscribes as well, so that number might be a bit inflated. But, if you add these contacts to a list, the unsubscribes will not be added, so no worries there! If you have any other questions about the Advanced search, or contacts that aren't on any lists, let us know and we can help! Thanks for reaching out to the Community with your query!
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