https://www.howto-outlook.com/howto/fix-imported-imap-folders.htm
Method 1: Automated fix with a script
The script below will fix the incorrect folder class property for you so that it will become a regular mail folder again just like all the others.
After running the script, you’ll immediately see all your emails again, have Follow Up flag support and all other aforementioned issues will be gone. You don’t even need to restart Outlook!
The script allows you to fix a single folder, a folder and its subfolders or your entire mailbox at once. It will automatically recognize folders that don’t need any fixing and won’t make any changes to these either.
- Download the file; fiximportedimapfolders.zip
- Open or extract the zip-file, and double click on;
FixImportedIMAPFolders.vbs -
Click on Outlook in the Taskbar to see the “Select Folder” dialog.