<-- Last I looked, the Microsoft support thread was 20+ pages of people frustrated with there being no category support for mail in the mobile app. There still isn't.

And it's gotten worse. The #Outlook web interface used to provide an autosuggestion when searching "category: blue" for example when typing "blue". That's been removed since June-ish 2024. You can still type the "category:" part yourself but no autocomplete available.

Sure seems like #Microsoft is #deprecating Categories.