I faced a situation where my inbox was filled with repeated emails, so I searched about remove duplicate emails in Mac Outlook to figure out the best way to clean it up. From what I learned, duplicates usually occur due to sync issues or importing the same data multiple times. Large mailboxes and multiple device access can make the problem worse. Manually deleting duplicates works, but it becomes very time-consuming if the mailbox is big. In my case, I first fixed the sync settings to stop new duplicates from appearing. Then I cleaned the existing ones to free up space. It made a huge difference in performance. Now Outlook runs much smoother.