We want to make sure you are all kept up to date with any major changes to the Windows experience. Microsoft Outlook for Windows 2016 (and later) are set to upgrade to the modern logon experience. You may be used to seeing the below pop up when entering your credentials:
This will now be changing to a new, more modern experience as below:
This is nothing to worry about, and it is has been done to improve the security of Office 365 and the services associated with it. With the change in logon experience, although primarily it does look different; in the background this change improves security and ensures that your credentials are not stored directly on your device. Furthermore, if there are any changes in your device or locations out of the ordinary; you will be prompted to further authenticate the logon.
I hope this blog helps and see you next time!