Using Classic Outlook on Windows for personal email, calendar, and contact management
Got it. Try exporting the PST into a BRAND-NEW PST
This is not the same as re-importing the same file. Exporting rewrites every message and folder, stripping the bad flags.
Steps
- Open Microsoft Outlook
- File → Open & Export → Import/Export
- Choose Export to a file
- Select Outlook Data File (.pst)
- Select the entire imported PST (top level)
Check Include subfolders - Save as a new PST (new filename, new location)
Close Outlook
Reopen Outlook
- Remove the old PST
Open the new PST