Windows 11

How to Delete Duplicate Emails in Outlook 365

Outlook 365 is a popular email client used by millions of individuals and businesses around the world. However, one common issue that users often encounter is the presence of duplicate emails in their inbox. Duplicate emails can clutter your mailbox, make it difficult to find important messages, and waste valuable storage space. In this article, we will explore various methods to delete duplicate emails in Outlook 365, helping you streamline your inbox and improve your email management efficiency.

Understanding Duplicate Emails

Before we delve into the methods of deleting duplicate emails, it is important to understand what causes duplicate emails to appear in the first place. Duplicate emails can occur due to a variety of reasons, including:

  • Syncing issues between multiple devices
  • Incorrect email rules or filters
  • Software glitches or bugs
  • Importing or migrating emails from another email client

Regardless of the cause, duplicate emails can be a nuisance and can disrupt your email workflow. It is crucial to address this issue promptly to maintain an organized and efficient inbox.

Method 1: Using the Clean Up Tool

Outlook 365 offers a built-in Clean Up tool that can help you remove duplicate emails from your mailbox. Follow these steps to use the Clean Up tool:

  1. Open Outlook 365 and navigate to the folder where you want to delete duplicate emails.
  2. Click on the “Home” tab in the Outlook ribbon.
  3. In the “Delete” group, click on the “Clean Up” button.
  4. From the drop-down menu, select the “Clean Up Folder” option.
  5. Outlook will analyze the selected folder and identify duplicate emails.
  6. A dialog box will appear, asking for confirmation to delete the duplicate emails. Click on “OK” to proceed.

The Clean Up tool will remove the duplicate emails from the selected folder, helping you declutter your mailbox. However, it is important to note that this method may not be suitable for large folders with a significant number of duplicate emails, as it can be time-consuming and may not catch all duplicates.

Method 2: Using the Remove Duplicate Items Tool

If the Clean Up tool does not effectively remove all duplicate emails, you can utilize the Remove Duplicate Items tool, which is a third-party add-in for Outlook. This tool offers advanced features and algorithms to identify and delete duplicate emails more efficiently. Follow these steps to use the Remove Duplicate Items tool:

  1. Download and install the Remove Duplicate Items tool from a reputable source.
  2. Launch Outlook 365 and navigate to the folder where you want to delete duplicate emails.
  3. Click on the “Add-Ins” tab in the Outlook ribbon.
  4. Locate and click on the “Remove Duplicate Items” button.
  5. The tool will scan the selected folder and display a list of duplicate emails.
  6. Review the list and select the duplicate emails you want to delete.
  7. Click on the “Delete” button to remove the selected duplicate emails.

The Remove Duplicate Items tool offers a more comprehensive approach to removing duplicate emails and can handle larger folders more efficiently. However, it is important to choose a reliable and trusted tool to ensure the safety and integrity of your emails.

Method 3: Using Outlook Rules

Outlook allows you to create rules that can automatically manage your emails, including identifying and deleting duplicate emails. Follow these steps to create a rule to delete duplicate emails:

  1. Open Outlook 365 and navigate to the folder where you want to create the rule.
  2. Click on the “File” tab in the Outlook ribbon.
  3. Click on the “Manage Rules & Alerts” button.
  4. In the “Rules and Alerts” dialog box, click on the “New Rule” button.
  5. Choose the “Start from a blank rule” option and click on “Next”.
  6. Select the “Check messages when they arrive” option and click on “Next”.
  7. In the next window, leave all conditions unchecked and click on “Next”.
  8. A warning message will appear, asking if you want to apply the rule to all messages. Click on “Yes” to proceed.
  9. In the next window, select the “Delete it” option and click on “Finish”.

The rule you created will automatically delete any duplicate emails that arrive in the selected folder. However, it is important to periodically review and adjust the rule to ensure it does not delete any legitimate emails.

Method 4: Manual Deletion

Manual Deletion
Manual Deletion

If you have a small number of duplicate emails or prefer a more hands-on approach, you can manually delete duplicate emails in Outlook 365. Follow these steps to manually delete duplicate emails:

  1. Open Outlook 365 and navigate to the folder where the duplicate emails are located.
  2. Sort the emails by the “Subject” column to group duplicate emails together.
  3. Select the duplicate emails you want to delete by holding down the “Ctrl” key and clicking on each email.
  4. Right-click on one of the selected emails and choose the “Delete” option.

This method is suitable for users who prefer a more hands-on approach and have a limited number of duplicate emails. However, it can be time-consuming and may not be practical for large folders with numerous duplicates.


Duplicate emails can be a frustrating issue in Outlook 365, but with the right methods and tools, you can effectively delete them and maintain an organized inbox. Whether you choose to use the built-in Clean Up tool, a third-party Remove Duplicate Items tool, create rules, or manually delete duplicates, it is important to regularly address this issue to optimize your email management efficiency.

By following the methods outlined in this article, you can streamline your inbox, save storage space, and improve your overall email experience. Remember to choose a method that suits your needs and preferences, and always backup your emails before performing any deletion actions to avoid accidental data loss.

Frequently Asked Questions (FAQ)

Q: Can I recover deleted duplicate emails in Outlook 365?

A: Once you delete duplicate emails in Outlook 365, they are moved to the “Deleted Items” folder. If you have not emptied the “Deleted Items” folder, you can recover the deleted duplicate emails by navigating to the folder and moving them back to the desired location.

Q: Are there any risks involved in using third-party tools to delete duplicate emails?

A: While third-party tools can be effective in removing duplicate emails, it is important to choose a reputable and trusted tool to ensure the safety and integrity of your emails. Always research and read reviews before installing any third-party add-ins or tools.

Q: How often should I check for and delete duplicate emails?

A: The frequency of checking for and deleting duplicate emails depends on your email usage and the volume of incoming messages. It is recommended to perform regular checks, especially after importing or migrating emails, to prevent the accumulation of duplicate emails.

Q: Can I prevent duplicate emails from appearing in Outlook 365?

A: While it is not always possible to completely prevent duplicate emails, you can minimize their occurrence by ensuring proper syncing between devices, reviewing and adjusting email rules, and regularly organizing and decluttering your mailbox.


I am a technology writer specialize in mobile tech and gadgets. I have been covering the mobile industry for over 5 years and have watched the rapid evolution of smartphones and apps. My specialty is smartphone reviews and comparisons. I thoroughly tests each device's hardware, software, camera, battery life, and other key features. I provide in-depth, unbiased reviews to help readers determine which mobile gadgets best fit their needs and budgets.

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