How to Combine multiple Outlook PST Files
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If you use Microsoft Outlook regularly, you might find yourself with multiple PST (Personal Storage Table) files that contain important emails, contacts, and other data. While having multiple PST files can be useful for organizing your data, it can also make it difficult to find the information you need quickly. One solution to this problem is to merge your PST files into a single file, but doing so can result in duplicate items that take up unnecessary space. In this article, we will explain how to merge PST files without duplicates.

How Does Duplicate Data Created in PST Files?

Duplicate data can occur in PST files in several ways. One of the most common reasons is when a user imports data from an old PST file or other data sources. During the import process, users may accidentally import the same data more than once, leading to duplicates.

Another way duplicate data can be created is when users archive email messages. If a user archives email messages to a PST file, the same message may appear in both the original mailbox and the PST file, creating a duplicate.

Sometimes, synchronization issues between Outlook and the email server can cause duplicates. For example, if a user deletes a message from the mailbox on their email server but the deletion does not get synchronized with their local PST file, the same message will remain in the PST file, creating a duplicate.

Lastly, some add-ins or third-party applications may inadvertently create duplicates. These applications may interact with Outlook or PST files in a way that leads to the creation of duplicate data.

To avoid duplicates, it’s important to regularly manage and clean up PST files. Users can use specialized software, such as below mentioned, to identify and remove duplicates. By regularly maintaining PST files and removing duplicates, users can ensure their email management processes are streamlined and efficient.

Also Read: How to Migrate Outlook Emails to Office 365 -Two Effortless Methods

Why It is Needed to Merge PST Files Without Duplicates?

Merging PST files without duplicates is an important task that can improve the organization and efficiency of your email management system. There are several reasons why you may need to merge PST files without duplicates:

  • Simplify Email Management: Having multiple PST files can make it difficult to find and access specific emails or attachments. By merging all your PST files into one, you can simplify your email management and quickly locate the emails you need.
  • Avoid Duplicate Emails: Duplicate emails can clog up your mailbox and make it difficult to identify the most recent and relevant messages. By merging PST files without duplicates, you can ensure that you only have one copy of each email and keep your mailbox clean and organized.
  • Improve Performance: Having multiple PST files can slow down the performance of your email client, especially if the PST files are large in size. Merging your PST files can improve the performance of your email client and make it easier to access and manage your emails.
  • Backup and Restore: Merging PST files without duplicates also makes it easier to back up and restore your emails. Having all your emails in one PST file makes it simpler to create a backup and ensures that you do not miss any important messages.

Overall, merging PST files without duplicates can help you better manage your emails, avoid clutter and duplicates, and improve the performance of your email client. It is an essential task for anyone who wants to keep their emails organized and easily accessible.

How to Merge PST Files Without Duplicates Using Outlook?

Merging PST files in Outlook without duplicates is a great way to keep your emails organized and avoid confusion. 

Follow these simple steps to merge multiple PST files into one without duplicates:

Step 1. Create a Blank PST File

First, create a blank PST file where you can merge all the other PST files. To create a new blank PST file, go to File > Info and click on “New Items > More Items” and select “Outlook Data File”. Choose the location where you want to save the new PST file, type a name for the file, and click OK.

Step 2. Open the PST Files to Merge

Next, go to File > Open & Export and click on “Open Outlook Data File”. Browse and choose one of the PST files that you want to merge and click Open. Once the PST file is open, you can access all the mail folders and items from it.

Step 3. Export the PST File

Click on “File > Info > Open & Export > Import/Export”. Select “Export to a file” and then click Next. Choose “Outlook Data File (.pst)” and click Next. Make sure that the “Include subfolders” option is checked. Click Browse to choose the blank PST file and choose the “Replace duplicates with items exported” option. Click Finish. All the mail items in the Outlook data file (PST) will be exported to the blank PST file.

Step 4. Repeat for Additional PST Files

Repeat the process for all the other PST files you want to merge. Make sure to choose the “Replace duplicates with items exported” option to avoid duplicates. Depending on the number of PST files you need to merge, this process may take some time.

Step 5. Close the Outlook Data File

After the export, right-click on the Outlook Data File in the left pane and choose “Close ‘Outlook Data File'”.

By following these simple steps, you can merge multiple PST files into one without duplicates and keep your emails organized in Microsoft Outlook.

Must Read: Export Office 365 Mailbox to PST With Easy to Use Free Solutions

How to Merge PST Files without Duplicates Using a Smart Tool?

While a manual method may seem like a simple solution, it can be time-consuming, error-prone, and lacking in customization options. In contrast, using a specialized tool like SysTools PST Merge Tool can provide several benefits and make the process of merging PST files more efficient and accurate.

Here are the steps to follow:

Step 1.Run the software and click on the “Add Files” or “Add Folder” button to select the PST files that you want to merge.


Step 2.Choose the “Merge” or “Join” option according to your needs.


Step 3. Choose Merge PST files into New PST, Existing PST or Outlook Profile


Step 4. Select the destination where you want to save the merged PST file. You can merge the PST files into a new PST file, existing PST file or directly into your Outlook profile.


Step 5. Click on the “Merge” button to start the merging process. The software will merge all the selected PST files into one.


By following these steps, you can easily merge PST files without duplicates and improve your email management. 

Benefits of Merging PST Files Without Duplicates

Merging PST files without duplicates can offer several benefits, including:

  • Reduced clutter – By merging multiple PST files into a single file, you can eliminate the need for multiple files, making it easier to manage and organize your data.
  • Improved efficiency – When you have all your data in one PST file, it’s easier to find what you’re looking for and work more efficiently.
  • Better data management – Merging PST files without duplicates ensures that you don’t have multiple copies of the same data, making it easier to manage and backup your files.
  • Reduced risk of data loss – Having multiple PST files increases the risk of losing important data if a file gets corrupted or lost. Merging PST files can reduce this risk by consolidating all your data into one file.
  • Improved collaboration – If you need to share your Outlook data with others, having one consolidated PST file makes it easier to do so, rather than sharing multiple files with different people.
  • More efficient backup and archiving – By merging your PST files, you can back up or archive your data more efficiently, since you only need to deal with one file rather than multiple files.

Why Choose Software Over Manual Method to Remove Duplicate Items in PST?

When it comes to merging PST files and removing duplicate items, there are two options: a manual method or software. While the manual method can work for small or simple PST files, using software is the better choice for several reasons:

  • Time-saving – Using software can save you a lot of time, especially if you have many PST files to merge. The software automates the process, so you don’t have to manually search for duplicate items.
  • Accuracy – Manually removing duplicate items can be time-consuming and prone to human error. The software uses advanced algorithms to detect and remove duplicate items accurately.
  • Cost-effective – While some software solutions may come at a cost, it’s still a more cost-effective solution than hiring someone to manually go through your PST files to remove duplicates.
  • Simplicity – Using software is typically a more straightforward and user-friendly option than the manual method, which requires advanced technical skills and knowledge.
  • Customization – Some software solutions offer options to customize the merging process, allowing you to choose specific folders or items to merge or exclude.

Overall, choosing software over the manual method to remove duplicate items in PST files is a more efficient, accurate, and cost-effective solution. It saves you time, reduces the risk of errors, and simplifies the process of merging multiple PST files.

Must Read: How to Create Shared Calendar in Outlook: A Comprehensive Guide


Merging PST files without duplicates is essential to optimize storage space and access to mailbox items efficiently. Whether you have multiple PST files from different email accounts or backups, merging them can help streamline your email management process. While it’s possible to manually merge PST files, using software can save you time, reduce errors, and provide more customization options. 

There are several software solutions available, including the above mentioned SysTools PST Merge Tool, that make the process easy, quick, and accurate. Regardless of the method you choose, merging your PST files is a crucial step to managing your mailbox effectively.

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