How to enable Unread view in Boomerang for iOS

To find your unread emails, you can use the Intelligent Query search term "is" and select Unread in the Search Bar. If you'd prefer, you can also have an Unread tab displayed below your Inbox in Boomerang as well:

How to display Unread emails under your Inbox

Tap the Menu Icon in the top left corner of your screen.

Tap Settings.

Tap the corresponding account under Account Settings.

Toggle the Display Unread View switch On.

An Unread tab of your Inbox will now be selectable in the side navigation pane.