Using New Outlook on Windows for personal email, calendar, and contact management
Hi!
Sometimes folders get accidentally dragged into another folder(like you mentioned you're in the process of moving them one-by-one and accidentally it might have been put to another folder). You need to check ALL folders (no shortcut for this action) expand all of them one-by-one.
You can also search for a specific subject or sender that is included on the folder that is missing.
- In Outlook or webmail, use the search bar and change the scope to "All Mailboxes" or "All folders."
- If emails from the folder show up, check the folder path in the reading pane or in the properties.
Try checking on the Webmail(if using a Gmail or Outlook.com account) check all folders and search specific sender or subject that you can recall. you can check deleted item as well here.