Symptoms:

• Emails not syncing
• Calendar events missing
• IMAP errors

Cause:

• Corrupt OST/PST files
• Recent Windows updates (e.g., KB2837618)

Resolution:

Run ScanPST.exe to repair PST/OST files

1. • Path: C:\Program Files (x86)\Microsoft Office\root\OfficeXX\scanpst.exe
2. Uninstall problematic updates via Control Panel > Programs
3. Recreate OST file by deleting it and restarting Outlook

SCANPST.exe is located in 

C:\\Program Files (x86)\\Microsoft Office\\root\\OfficeXX\\ (