The navigation pane appears on the left side of the Outlook for Mac window and is how you switch between the different views of Outlook, such as Mail, Calendar, Contacts, Tasks, and Notes. In addition, when you are working within a view, the navigation pane displays the folders within that view. When you click a folder in the navigation pane, that folder becomes the active folder and you can work with the items within it.
Do any of the following:
Hide the navigation pane
On the View menu, click Navigation Pane.
Tip: If you hide the navigation pane, the view switcher is also hidden. To change views while the view switcher is hidden, on the View menu, point to Go To, and then click a view.
Minimize the view switcher
You can minimize the view switcher to make more room in the navigation pane.
Point to the horizontal splitter bar between the folders and the buttons, and drag the bar up or down when the pointer turns into a double-headed arrow . If you drag the horizontal splitter bar to the bottom of the navigation pane, all the large buttons become small buttons and appear as a single row of icons at the bottom of the navigation pane..
Turn off the unified inbox
By default, the Outlook folder list groups similar folders, such as inboxes, from all your mail and Microsoft Exchange accounts. This feature can make it easier to read all your messages at one time, without having to move around between mail folders. If you want, you can turn off this feature so that each account and all its folders are separated in the folder list.
On the Outlook menu, click Preferences.
Under Personal Settings, click General .
Under Folder list, clear the Group similar folders, such as Inboxes, from different accounts check box.