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5 effective methods to Remove Duplicate Items in Microsoft Outlook

Outlook falls in the center of professional communication and email exchange. Avid users can generate a lot of Outlook items that swell up PST file size and consume a lot of One Drive or Hard drive space.

Importing Outlook items from archives or PST files is very common. When you import items in MS Outlook, and the duplicate detection option is turned off, Outlook skips removing the duplicate items during the import process. Once the import is completed, remove duplicate items can be very tedious.

In this article, you will learn multiple approaches on how to effortlessly remove duplicate items in Microsoft Outlook

Why do you need to Delete Duplicate items on Outlook?

  1. Duplicate items increase the size of the Outlook Data files unnecessarily
  2. If Outlook is configured with Exchange Server or Office 365, duplicate items will increase the size of the Exchange/Office 365 mailbox.
  3. Duplicate data in Outlook if backed up will waste the backup space.
  4. Duplicate items lead to unnecessary confusion affecting your productivity.

How to Remove duplicate items on Outlook


Note -  During the implementation of the below procedure of removing the duplicate items in Microsoft Outlook you might encounter a data loss scenario, hence we recommend you to take a backup of your valuable data using Remo Outlook Backup and Migrate.

Configure the rules appropriately

Check whether the Outlook rules are configured correctly or not. If rules are not set appropriately, it will create confusion among different email folders. Configure the rules correctly. Also, ensure that only a single instance of the Outlook application is running. Close the extra instances of Outlook.exe using the Task Manager on your system.

Always select “Do not Import Duplicate Items” while importing Outlook items

Whenever you import files to Outlook using the Import/Export option, make sure to select “Do Not Import Duplicate Items” option towards the end of the Import process to avoid the import of duplicate items in the application

Clean up the duplicates in the Inbox

Follow the methods mentioned below to clean up in the duplicates in the inbox. Outlook has a number of utilities and add-ins, which can help you to clean up duplicate emails easily.

  • Start Outlook.
  • Select a mailbox folder.
  • Select Home > Cleanup. Now, configure the below options:remove duplicate items from Microsoft Outlook
  • Clean up Conversation will delete and move the duplicate emails that are in the conversation.
  • The Folder will remove the duplicate emails from any particular folder
  • Clean Up Folders and Subfolders will clean up the duplicate folders and subfolders
  • Right-click the Deleted Items folder and click Empty Folder that will permanently delete the emails.

Setting the inbox update frequency

Setting high inbox update frequency can mitigate the risk of duplication of the Outlook items.

  • Open Outlook
  • Go to Send/Receive option on the top corner
  • Select Define Send or Receive Groups.
  • Set the value within 15-30 minutes and click on OK.


If you found duplicate files in your mailbox, it could be due to the closing of the server connection and settings of the Antivirus application, which often creates duplicates due to server connections.

While implementing any of the above-mentioned procedures you often might encounter data loss scenarios, hence we recommend you to take backup using Remo Backup and Migrate as mentioned in the above section.

Remo Outlook Backup and Migrate

Built with a simple one-click to backup methodology, Remo Outlook Backup Tool is an exclusive tool that can help you take a complete backup of Outlook with all its attributes including Outlook rules and settings. You can also be allowed to schedule an auto-backup of the Outlook files on the desired time. This tool supports migration from one computer to another within a matter of few clicks. The software also supports Outlook to Office 365 migration.

Download Remo Recover for Recycle Bin recovery


The above article summarizes on how to remove duplicate items in Outlook with the help of various approaches, If you have any further queries regarding the article, make use of the comment section in the section below.

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Tony Landry

Tony Landry is a Web Content Editor at Remo Software. He loves to write, edit, and manage content for users trying to troubleshoot and fix problems on Windows, Outlook, storage drives and Cloud storage networks.

He has published more than 200 articles in Remo Software blog. He actively engages in research and problem-solving techniques to consistently generate great web content. Fixing various hardware problems on computer and storage devices along with a great knack for fixing Outlook errors, Tony is also the fun-time IT guy for all his work friends. He lives in the San Francisco Bay Area and enjoys cycling.

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