If you have duplicate emails in the Outlook PST file, TrustVare Outlook PST Duplicate Remover can be a useful solution. I’ve used this tool & found its interface to be quite simple. It scans even large PST files quickly & preserves the original data.
Key Features:
Remove Duplicate Emails from PST Files
Scanning based on Subject, Date, Sender, etc.
Support for Bulk PST Files
Data Integrity Completely Protected
Fast and Accurate Scanning
Compatible with All Windows Versions
Simple & Friendly Layout
This utility might be very useful if Outlook is slow or if the size of the PST file has increased.