Hi @Scheffer, William ，
Currently new Outlook does not support the ability to sort by Categories. A potential work around is that you can pin your favorite category as well.
You can sort the message list by clicking on 'Filter' at the top right side of the message list pane and selecting an attribute to focus on. The developers are working on supporting additional attributes, which will be available in future releases.
The new Outlook is not yet complete, and some options may not be available or work as expected. You can switch back to the classic Outlook at any time by clicking the toggle button in the top right corner of the window.
Besides, many features of our current products are designed and upgraded based on customers’ feedback. With requirements like this increase, the problem may well be released in the future. I’ve tried submitted this feature request in forum. What I can do for you at present is to submit a suggestion for you, and you can also make a suggestion via this link.
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