View: Sort Inbox Items
By default Outlook displays your E-mail messages sorted By Date. You can change the Inbox sorting if you wish.

4. Try it: Change the Inbox Sort Order
Go to Message List ->Items by Date.
SORT BY: date.
ORDER: oldest on top.

What Do You See? The new E-mail message will be displayed on the bottom.

Try This, Too: Change it Back
Go to Message List ->Items by Date.
SORT BY: date.
ORDER: newest on top.

Keep going...

Outlook->Message List->Items by Date