A great way to organize email is Categories

A great way to organize email in Outlook is Categories. Set up categories by using the Categorize button in the Tags group, and choose All Categories. If you like, you can assign a keyboard shortcut to make it easier to apply categories to an email message.

After processing your email, categorizing as you go, click the Categories column title at the top twice. The first time sorts noncategorized items to the top. The second puts the categorized ones at the top. On the View tab in the Arrangement group, click the Expand/Collapse button to collapse all groups. Then process one category at a time.