Mail app for Windows 8.1 - Display social updates and newsletters in the main inbox
By default the Mail app of Windows 8.1 will organize newsletters and social updates in seperate folders. If you only receive a few of these messages each month, then you don't necessarily want to have them in seperate folders.
To get the newsletter and social updates displayed in the Inbox folder:
Open the Mail app.
Press the Windows key + C to bring up the Charms Bar.