How to keep the Folder Pane expanded in Outlook
Outlook’s Folder Pane displays all folders which lets you quickly move between folders and views. Minimise the Folder pane, you will no longer be able to see your folders. As a result, some users get puzzled as to how they can bring back the expanded Folder Pane view. There are a few ways that you can do this:
Change the Folder Pane Setting
Select the View Tab | Layout | Folder Pane
Select the Normal Option
The Folder Pane should now reappear on the left side of Outlook.
Use the Pin Icon
Select the ‘>’ button to expand the Folder Pane.
Then click the pin icon to pin the Folder Pane. That way, it will stay expanded even when you click outside the pane.
Alt + F1 shortcut with Outlook Folder Pane
The keyboard shortcut Alt + F1 is very handy with the Folder Pane.
Press Alt + F1 to cycle through the side-pane modes; Normal. Minimized or Off.
This works in any Outlook view. Viewing a Calendar and pressing Alt+F1 will show/hide the monthly calendar at left.