In MS Outlook, how Can You Remove Duplicate Items?

Updated On - January 16, 2023 by Deepika Singh |

Reading Time: 6 minutes

When the duplicate detection feature is turn off when importing things into MS Outlook, Outlook skips the duplicate items. You won’t be able to simply remove duplicate Outlook items once the import is finish. Concentrate on the phrase “duplicate items are difficult to eliminate.” This mean you can get rid of the duplicates, but it won’t be easy. Read through this entire page to learn how to remove duplicate items in Microsoft Outlook 2019, 2016, and all prior versions.

How Can Duplicate Outlook Items Be a Problem for You?

Microsoft Outlook is one of the most popular amongst all the applications included in the Microsoft Suite. Outlook necessitates a large amount of resources in order to run smoothly. Duplication of messages and emails is a typical occurrence for Outlook users. We mentioned a few issues below that you may encounter at some point of time.

  • Duplicate emails causes a slew of problems. The user has no way of knowing whether or not an email has been answered. If you keep replying to the same email many times, it will cause more confusion among team members and clients.
  • Duplicate emails and messages unnecessarily increase the size of Outlook data files. Outlook performance deteriorates. It has negative impact on business efficiency. It takes longer to access and reply to new emails.
  • Duplicate items will raise the size of the Exchange/Office 365 mailbox if Outlook is set up with Exchange Server or Office 365.
  • Outlook backups require more storage space, and if you choose to store backups on external cloud storage, you will be charge for additional storage.

Reasons that lead to duplication of email messages

There are numerous explanations for this, which we will describe below.

  1. Incorrect rule configuration

When you get an email message, if the rules are configured wrong, it will cause confusion. As a result, the emails are duplicate.

  1. Messages are sent and received in short intervals

When the inbox is updated infrequently, the emails and other data in the mailbox are not synchronized, resulting in data duplication.

  1. Account setup error

If the same email account is used on multiple devices, such as laptop and a Smartphone, the incoming message will be synchronize many times. One of the causes of email duplication in the Outlook mailbox could be this.

  1. Mailbox settings aren’t right

If the mailbox parameters are specified incorrectly while creating an account in Outlook, it is likely that the same email and any message may be receive many times.

  1. Technical Problem

Duplication of Outlook items might also be caused by a technical fault with the mail server. If you enable the option to “Leave Messages on the Server,” this is a common occurrence. When two or “transfer a copy to” rules are applied to specific incoming emails, Microsoft Outlook’s incorrect setup is regulated. This frequently results in email duplication. Duplication of emails can also occur when multiple PST files are combine into a single file.

Whatever the causes for making several copies of a single message, it will slow down Microsoft Outlook’s productivity, so you should delete duplicate items from Outlook!

How Can You Check For Email Duplication in Outlook?

You can’t tell if an Outlook email is duplicated just by looking at it. To see if a message contains more than one email, you can examine different attributes of the message. For the comparison, you can utilize the following fields:

  • Subject
  • Text
  • Sender
  • Recipient
  • Attachment

When you do a search with such a field, the same email may appear multiple times if there are duplicates in the mailbox. You can search inbox emails using the fields given above and remove similar looking emails using the delete option in the application for a small number of duplicate emails. However, with a large number of duplicate objects, the work becomes more difficult.

Is it simple to get rid of duplicate files in Outlook 2019, 2016, 2013, or 2010?

It is very important to remove duplicated items from your mailboxes. If you have hundreds or thousands of such items, it will be difficult for you. It would be nearly impossible to manually delete those items if the quantity was even higher. In brief, manually eliminating duplicate items is a difficult operation, and Microsoft, sadly, does not give an easy solution for this issue.

How to remove duplicate items from Outlook?

Before you begin the process to remove duplicate items from Microsoft Outlook, you must first determine the source of the problem and then resolve it. However, if you are unable to do so, here is some assistance. Here are five methods for removing duplicate items from your Outlook mailbox.

1. Make sure the rules are set op correctly

Check to see that the Outlook rules are set up appropriately. If the rules aren’t specified correctly, it will lead to confusion among the many email folders. Make sure the rules are set up correctly. Also make sure that the Outlook application is running in a single instance. Using the task manager on your computer, end the extra instances of Outlook.exe.

2. When importing Outlook items, always select “Do Not Import Duplicate Items”

When utilizing the Import/Export tool in the Outlook application to import Outlook PST file objects such as mailbox folders or contacts make sure to select the “Do Not Import Duplicate Items” option near the conclusion of the procedure. This helps you to avoid importing duplicate items in the application.

3. Decide how often you want your inbox to be update

You should increase the frequency with which your inbox is updated. Go to Send and Receive in Outlook after you’ve opened it. Select Define Send or Receive Groups from the drop-down menu. Within 15-30 minutes, set the value.

4. Clear up your inbox

There are lots of applications and add-ins in Outlook that can help you effortlessly wipe up duplicate emails. To clear up your mailbox, follow the instructions below:

  • Open MS Outlook.
  • Choose a folder of your mailbox.
  • Select Home > Cleanup from the drop-down menu; configure the following options now:
  • Clean up Conversation – the duplicate emails in the conversation will be delete and moved by conversation.
  • Folder Clean up can eliminate duplicate emails from any folder.
  • Clean up Folders and Sub-folders removes duplicate folders and sub-folders from your system.
  • Empty the Deleted Items folder by right clicking it and selecting Empty Folder, which will permanently remove the emails.

5. Antivirus Software

It’s possible that you found duplicate contents in your email as a result of the server connection being close and the Antivirus applications settings being change. Emails that are not marked as received will create duplicates if the server connection is not properly shut down. To resolve this, browse through the Antivirus application documentation and disable the email protection. We do not advocate this approach since stopping the antivirus can cause serious problems if a virus is sent to your computer via email.

6. Outlook Duplicate Remover from Regain Software

For permanent removal of Outlook duplicate items, you can use a reputable third-party Outlook Duplicate Remover tool. The third party solution is design in such a way that duplicate emails and other duplicate Outlook objects are no longer an issue.

Free Download100% Secure Buy NowPrice: $29

Regain Outlook Duplicate Remover is one such application. Duplicate items in Outlook are automatically found and remove by the software. It is the most effective and tried method for removing Outlook duplicates items. It gives you a lot of choices for finding duplicate items, such as, specifying a date range to identify duplicates. There is also a free version of the software that allows you to eliminate duplicate items. With this free Outlook Duplicate Remover application, you may also remove 20 items from each folder.

To delete duplicate items from MS Outlook, follow these steps:

  1. Download and run Outlook Duplicate Remover tool on your system
  2. Now, click ‘Add File’ to upload PST files for scanning
  3. Click the ‘Search Duplicate Items’ option to find duplicate items in the file
  4. Now software will show you the number of duplicate items found in your PST file
  5. Press the ‘Remove Duplicate Items’ option to remove them
  6. Finally, all duplicate items are removed and now your PST file contains no duplicate email messages.

As you may have seen, there is no manual way to identify and delete duplicate items in Outlook other then reading and deleting each email. You can save time by using an automated solution such as Regain Outlook Duplicate Remover.  


Duplicate items in Outlook can cause a slew of problem. Users are confuse by them, and it takes up a lot of space in the data file, making PST files subject to corruption and errors. Despite the fact that Outlook users can take different precautions to avoid this problem, removing identical emails from the mailbox is tough unless you employ a professional application. As a result, many Outlook users uses Outlook Duplicate Remover tool developed by Regain Software to eliminate duplicate email messages from PST files.

Author: Deepika Singh

My self Deepika Singh working as a Technical Writer in Regain Software. Having 4+ years experience in Writing Technical blogs, Manual Guides and Articles. I am working on all Regain Software products.

One thought on “In MS Outlook, how Can You Remove Duplicate Items?”

  1. Avatar Antje Klein says:

    I never realized how easy it was to remove duplicate Outlook items. I would have been wasting a lot of time trying to figure it out on my own! But with your instructions, I was able to easily clean up my Outlook inbox and get rid of all the duplicate items. Thanks for providing such great advice.

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