If you are an Office 365 subscriber you may notice (or have already noticed) a few changes with Outlook.
Outlook is pushing updates through to the desktop for Office 365 subscribers. The updates will sometimes force you to login to your Office 365 account. After the updates complete, you will see a bit of a new look for Outlook.
The goal here is not just to annoy the heck out you by changing the look and feel, they are also moving Outlook to operate the same way both on the desktop and online.
By the way, if you’ve not yet tried Outlook online, I suggest you give it a shot. It is highly functional and very quick.