Above the header in your folder you'll see the following buttons:
"All mail", "Unread", "Personal", "Notifications", "Mailing lists" and pinned sorting.
"All mail", "Unread", "Personal", "Notifications", "Mailing lists" and pinned sorting.
In fact, I'm amazed that most other mail clients / providers haven't taken this further than Google. I mean, it would be great with bayesian filtering for everything (labels, folders, categories, stars, whatnot). I would love to be able to train it to filter email into different folders based on me just clicking "Belongs here" / "Does not belong here".