If trying to clean up a large Outlook PST file that has a lot of duplicate emails, contacts, calendar, and manual steps do not work properly, you should try the best method. I can suggest a one tool becouse I'm used to it so you can try it before buying the full edition. The TrustVare Outlook Duplicate Remover, which quickly finds duplicate emails, contacts, calendar, etc, in the Outlook PST files and removes them without harming original data. It will handle a lot of duplicate items from Outlook PST files without downloading any other application. You should try the free trial before deleting duplicate Outlook PST files ot will give you a preview option.