- First, delete the Outlook Folder Cache file(s).
- Modify Outlook’s folder view settings or recreate your mail profile.
- Check to see if the Outlook Client is fully up-to-date.
- Run the Outlook Inbox Repair Tool (ScanPST).
- Check to see if the antivirus/firewall applications are blocking Outlook.
- Use a trusted third-party PST recovery tool.