When Microsoft rolled out Outlook’s Focused Inbox a year or so ago, it announced that it would discontinue their support for the Clutter Folder in Outlook.
Well, that time is fast approaching: Microsoft just announced that January 31, 2020 is the final sunset date for Clutter—about 11 months away. So it may be time to make the transition to Focused, if you like the auto-filtering that Clutter offers.
I blogged about Focused Inbox here: https://www.michaellinenberger.com/blog/what-about-outlooks-focused-inbox/
And I have a full description of the differences between these Clutter and Focused Inbox, and how to switch from Clutter to Focused, in Lesson 2.9 in the the Outlook Inbox Ninja Video Course.