In Gmail, how to find messages that are in the 'All Mail' folder, but nowhere else? [duplicate]

Question

In Gmail, how does one determine which email messages are in All Mail, but nowhere else?

I'm referring to email messages that are not in the Inbox (or another folder) and do not have any labels assigned.

Answer 1

In Apple Mail (served by Gmail) you can create a Smart Mailbox with these conditions.