Last updated on February 17th, 2024 at 05:00 pm

Are there some identical copies of emails in the same PST file? Do you want to delete them but don’t know how to do so? So don’t worry because this article has your solution. Here we will talk about ways to easily remove duplicate emails from OST/PST files.

MS Outlook is the application that enables users to access and manage their email profiles from their desktop. Some of the functions that Outlook supports are email sharing, contact management, calendar management, taking notes, etc.

Outlook stores all that data locally in OST and PST files. These files help users access their data locally in the absence of a connection to the Internet or server.

In some scenarios, a situation arises where Outlook generates multiple identical copies of data items and saves them inside data files. A similar issue arises with emails, Outlook generates multiple email copies in the data files, which can cause many problems for users.

Also Read: – How to Delete/Remove Duplicate Outlook MSG files?

Reasons for Duplicate Emails in Outlook files

  • Synchronization Errors: – Sometimes a connection failure between the Outlook client and the mail server results in the creation of multiple identical emails.
  • Rules and Filters: – The same email may be entered multiple times due to improper configuration of mail rules and filter settings. As a result, users get multiple identical copies of emails in a single PST file.
  • Outlook Add-ons: – Unsupported, incompatible or faulty third-party add-ins can also be a cause.
  • Corruption in PST: – Corrupt is one of the common reasons for the generation of copies of similar Outlook items in data files.
  • Importing data files: – Importing data from other data files into existing PST/OST files may generate copies of Outlook items.

Method 1: – Erase Outlook Email Duplicates with “Clean Up” tools

Using the inbuilt “Clean Up” tool of MS Outlook remove email duplicates easily by following these steps: –

  • Launch the MS Outlook application on your computer.
  • Select the folder from which you want to remove duplicate emails.
  • After folder selection, hit the Home tab from the top Outlook ribbon.
  • Find the “Clean up” icon and click on it in the Delete group.
  • From the drop-down menu, select one of the 3 available clean-up options: –
    • Clean-Up Conversation: This option removes unnecessary emails within a conversation thread.
    • Clean Up Folder: – Using this option erase redundant messages from the chosen folder.
    • Clean Up Folder & Sub-Folder: – Delete redundant emails from the chosen folder and their sub-folders.
  • With your selected mode, a new screen will appear with a confirmation dialogue.
  • Simply click on the “Clean Up” button to start deleting email copies and click OK on the next screen once it is complete.

Note: – Using this method users will delete duplicate email copies within the conversion or folder and those copies will be moved to the Deleted Items folder.

Method 2: – Automated Tool to Remove Outlook Email Duplicates

All users must try a specialized solution for deleting identical Outlook emails from data files. The best available option for this task is eSoftTools Outlook Duplicate Remover Software.

This is an advanced and multi-featured utility to ease copies of Outlook from both Outlook PST and OST files. It can remove duplicates within the folders as well as across all folders of Outlook data files. Additionally, it allows you to search emails and delete specific types of emails with different options.

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How to Remove Duplicate Emails from OST/PST file of Outlook?

  • Download and run the Outlook Duplicate Remover software.
  • Press the “Select PST or OST file” button, and choose a file adding mode: –
    • Add Single PST or OST file: – search or add a single data file (PST/OST).
    • Add Multiple PST or OST files: – add multiple data files or add a folder at once.
  • With the selected option add your data files and hit the Start Scanning button.
  • Scan data files, load their inner data and view Outlook items.
  • Choose the required folders and press the Remove Duplicates button.
  • Select and use the required options from the newly opened screen: –
    • Search Duplicate from: – Select the element you want to search for and remove duplicates. (“Mail”, “Contact”, “Calendar”, “Notes”, “Journal”, or “Tasks”).
    • For the search from Folder options: –
      • Search and Remove Duplicates within the folder
      • Search and Remove Duplicates Across folder
    • Email Duplicate Search options: – searching email copies by their associated attributes- From, TO, CC, Subject, Body, Attachment.
    • Mail Filtering: – select the dates and find email copies of PST files of the chosen date range.
  • Hit on the Browse button and choose a path where you want to save the resultant file.
  • Lastly, click on the Remove Duplicates button and start erasing the same emails from Outlook data files.


The multiple copies of emails in a single data file may be a reason for different problems in Outlook. To prevent those problems users must remove these email duplicates. With the above given methods users can safely accomplish this job. Try the inbuilt clean-up tool or the automated software as per your choice.

Get a free demo edition of this automated Outlook duplicate remover and easily delete duplicate emails from PST/OST files of Outlook.

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