How to Remove Duplicate Emails from PST? Best Solutions

Approved By Rollins Duke

Published On January 2nd, 2026

Reading Time 6 Minutes Reading

It is frustrating to have multiple copies of the same emails in PST, causing it to be oversized. Are you also fighting the same problem? If so, this blog post will guide you through the top 2 step-by-step 100% working methods to remove duplicate emails from a PST file.

PST (Personal Storage Table) file is a container for MS Outlook to store emails, contacts, calendars, etc., data copy on your desktop from the server. Due to a damaged PST file, misconfigured Microsoft Outlook settings, sync errors, mail server bugs, etc. The PST file has duplicate emails in it.

If you are looking for a solution to fix this overwhelming problem. Then you can easily delete duplicate emails from the PST file using 2 expert-guided techniques that we are going to discuss in this technical blog post. These two free and automated approaches include:

Use the Dedicated PST Duplicate Email Remover Offline Solution
Import PST with “Do Not Import Duplicates” Option

Now, before moving towards to actual solutions guide. Initially, let us discuss what the problems are that arise due to having duplicate emails in PST files.

What are the Major Problems that Arise Due to Having Duplicate Emails in PST?

Performance Issue with Oversized Outlook Data File: When duplicate emails accumulate in PST file. Whenever you try to open PST file in Outlook, due to duplicate emails Outlook data file size increases rapidly. This causes a performance lag in Outlook. Therefore, it is necessary to delete duplicate emails from Outlook PST.

Risk of PST File Corruption: If your Outlook data file has too many duplicate emails in it. Then there is a possibility that your PST file might get damaged, which causes a risk of losing crucial Outlook PST file data. Follow the methods below to delete duplicate emails from Outlook PST files.

Confusing During Searching & Sorting PST Files: Suppose if you are searching for specific emails in PST files. Then you might face challenges in searching and finding the required emails for duplication. However, on the other side, if you have fixed duplicate emails from the PST file, then it will be a much simpler process.

Migration Problems with PST Files: If you are planning to migrate PST to Office 365, Gmail, or some other platform, it contains duplicate emails. Then you might face challenges or errors during the migration process. Therefore, it is good practice to delete duplicate emails from PST before performing the migration task.

Completely Free Techniques to Delete Duplicate Emails from Outlook PST

If you are looking for a completely free approach to remove duplicate emails from PST. Then, you can either use the Outlook built-in import functionality. To uncover how to do so, you need to follow the step-by-step free techniques section. Please walk through each of the sections to overcome your conundrum.

How to Remove Duplicate Emails from PST Files Via PST Import Feature?

Launch Outlook Classic on your desktop.
Next, click on the File option and tap Open & Export.
After that, choose Import/Export > Import from another program or file.
Thereafter, tap on the Outlook data file (.pst) and browse the PST file to remove duplicates.
Now, enable the import without duplicates and click Next.
Finally, click on the Finish button to remove duplicate emails from PST via the Import feature.

Major Drawbacks of Using the Free & Manual Methods

This technique will not work if you are importing a PST file generated from a newer version of Outlook into an older version.
The above guided DIY approach is a very time-consuming process. If you need to remove duplicate emails from multiple PST files. Then you need to repeat the same set of steps from every PST file for deduplicating emails.
Your Outlook data file must be up to the size limit of 50 GB. Otherwise, your PST file might get corrupted, or you may face an error during the import process.
Another limitation of this DIY technique is that the user must have proper knowledge of using the Outlook import functionality. Non-technical users might face difficulty in removing duplicate emails from PST file using the free approach.

Professional Solution to Delete Duplicate Emails in Outlook PST

If you are looking for a more advanced solution that can remove duplicate emails from PST file from the folder or across the folder in a filter manner. Then you must try the free version of MailsWare Outlook Duplicate Remover. This advanced solution is designed to cleanup duplicate emails from Outlook and PST files directly in batch mode.

How to Remove Duplicate Emails in Outlook PST File? Working Steps

At the start, download and run the PST duplicate email remover utility on your PC.
Next, click on the Select Files or Select Folders option to load the PST for deduplicating emails.
After that, enable the folder containing emails for the deduplication process and click Next.
Thereafter, choose the mode of removing duplicate emails from Outlook PST file.
Then, choose the destination location for the deduped Outlook emails PST file.
Finally, click on the Extract button to get the removed duplicate emails from Outlook data file.

Concluding Thoughts

In this blog guide on the topic of how to remove duplicate emails from PST file, we have discussed both free and expert solutions. Before discussing the actual techniques, we have discussed the problems that arise due to duplicate emails in PST. Secondly, we have seen the working steps of the DIY approach. However, this method has many pitfalls. Therefore, we have discussed a more suitable PST duplicate email remover with some advanced features. Finally, we have seen the working steps of the smart solution to delete duplicate emails from PST file.