Removing duplicated messages in the email client MS Outlook

MS Outlook 2013 and higher
For the latest mail clients payed applications are available that will allow you to remove up to tens of duplicity messages using a trial version.
MS Outlook 2007 and 2010 - POP3

For email clients starting from MS Outlook 2010 version you can use the ODIR (Outlook Duplicate Items Remover). It is a freeware tool, installation file can be downloaded at the This add-in can't be used with the 64-bit version of Microsoft Office, but there are no problems when using the 32-bit version of Office installed on 64-bit version of Windows operating system.
The application detects duplicates as follows:
  • received emails - message-ID (unique message identifier)
  • sent emails - subject, date and time
  • un-sent messages - subject
Click the Download Now (direct link) button to download the ODIR.exe file. Once downloaded, run the installation from the directory where you saved the file.
Continue by starting the installation wizard. If you have not done so before starting the installation will require you to close MS Outlook.
Once installation of ODIR tool is completed, start MS Outlook.
Next instructions are intended for the Outlook 2010 version, but the installation procedure is almost identical for all earlier versions, with exception of the Add-in menu item location.
In MS Outlook 2003-2007 new menu item ODIR will appear.
doplnek ODIR pro MSO
MS Outlook 2010 will now show a new menu item Add-in, where you will find the ODIR item.
MSO 2010 - ODIR - doplnky
From the ODIR menu select Remove Duplicate Items.
New window will open with a list of Outlook items – select a folder (1.), which contains duplicity messages (for POP3 account ONLY Inbox). Clicking Remove duplicate items (2.) will start scanning of the folder.
  • ODIR will create a new folder ODIR_Duplicate_items inside the scanned folder into which all duplicated messages will be moved.
  • For IMAP account ODIR_Duplicate_items folder is not created during the scanning of your inbox - emails are instead moved into the Recycle Bin or marked as deleted. For all other folders ODIR_Duplicate_items folder is created same way as for POP3 account.
If you will not search other folders (for IMAP accounts), close the window by clicking the Close button.
Before deleting a folder ODIR_Duplicate_items, you can browse its contents.