How to Import PST to Office 365 Without Duplicates; Stepwise Solution

Import PST to Office 365 Without Duplicates

Published By Mohit Jha
Anuraag Singh
Approved By Anuraag Singh
Published On October 19th, 2023
Reading Time 10 Minutes Reading
Category Office 365

Do you feel the need to import PST to Office 365 without duplicates? The duplicates are of course the cause of consuming unnecessary space. These even hurt more when we want to migrate our data from Outlook to Office 365 and the process is taking too long due to these duplicated items.

Eventually, duplicates might lead to serious issues if not removed timely. So, let us discuss how to import PST files from MS Outlook to Office 365 with the help of manual as well as SysTools Office 365  Import Tool, avoiding duplicated items.

Table of Content

What are the Different Ways to Import PST to Office 365 Without Duplicating?

As a matter of course, we have two kinds of PST files. One is orphan PST and the other is already configured PST in Outlook. So we will learn how to import both kinds of PST files into Office 365 in the further section.

So first we will remove the duplicates from the orphan PST file using the Import/ Export function of Outlook. To do so, first, we will import duplicated data from a PST file into Outlook and then Export it.

Note: Orphan PST is a PST file that resides in some location other than MS Outlook in your system. It needs to be imported into Outlook.

5 Quick Steps to Import PST to Office 365 Without Duplicates

  • Step 1. Download, Install & Run Software.
  • Step 2. Choose Outlook & Office 365 as Platforms.
  • Step 3. Select Required Workload& Apply Filter.
  • Step 4. Authenticate Source & Destination Platforms.
  • Step 5. Select Users & Start Import Process.

Method 1. Manual Method to Import PST Skip Duplicates Using Outlook

The manual method through Outlook has 2 stages depending upon the user conditions. Both are discussed below. Follow the desired situation accordingly.

Stage 1. Import / Export PST File Avoiding Duplicates

If you have to import a PST file to Office 365 which is not imported into Outlook but is located in some other location in your system, then first import it to MS Outlook to avoid duplicates. And if you want to migrate an already configured PST inside Outlook to Office 365 then skip the first step and jump to step 2 to Export PST.

Stage 2. Import PST into Outlook Without Duplicates

  • Step 1. Open MS Outlook >> Go to File.
  • Step 2. Now choose the Open & Export option >> select Import/Export.
  • Step 3. Now choose Import from another program or file option inside the Import/Export wizard.
  • Step 4. Click Next.
  • Step 5. Choose Outlook Data File (.pst) option >> tap Next.
  • Step 6. Now browse the location of the PST file and select the option. Do not import duplicates >> Finish.

Important Tip: The option “Do not import duplicates” is used to prevent all the duplicates in the PST file that we are importing into Outlook.

Also Read: How to Export Office 365 Mailbox to PST via PowerShell

The duplicate-free PST file has been imported into Outlook and now you have to export it so that you can further migrate it to Office 365.

Stage 3. Export the Duplicate Free PST File

  • Open Outlook >> go to the File option
  • Choose the Open & Export option >> tap on the Import/Export option.
  • Click on “Export to a file” >> hit Next
  • Now choose the folder to export from and click Next
  • Next, browse to the location where you want to store your exported PST file >> hit Next

The above steps are for Outlook 2013 version. To know the Import/Export steps for other versions, refer to this article:

Now you have a duplicate-free PST file and you have to import it to Office 365. Let us see which methods can be used for the same.

Method 2. Reliable Techniques to Import PST to Office 365 Without Duplicates

It becomes the top priority to handle the PST files with care to avoid corruption when it comes to importing PST files to Office 365 without duplicates. To ensure a secure process, many IT admins recommend using professional software. The above-mentioned tool is designed to meet individual requirements and offers a seamless way to import PST files without any errors.

Detailed Software Steps Import PST to Office 365 Without Duplicates  

Follow the steps below to perform this task effectively.

Step 1. Download and run the above-mentioned tool on your computer.

Download Tool Purchase Now

Step 2. Choose Outlook as the source platform and Office 365 as the destination.

Step 3. Now from the workload selection screen, you have to select the mailbox categories such as emails, contacts, and calendars, that you want to import to Office 365. Apply date filter if required.

Step 4. Now navigate to the Source screen and select the folder path where the Outlook PST files are stored.

You have to put PST files in the folders (created with the name of the target O365 email IDs) as described below:

Create a folder in the root drive, like:

  • E:/PST/ all PST files of user1)
  • E:/PST/ all PST files of user2)
  • E:/PST/ all PST files of user3)


And then select the folder “E:/PST/” into our tool as “Import Folder Path”. Then click on the validate button to validate the required permissions. 


Step 5. Now move to the destination tab and use Office 365 admin credentials to log into the software. Click on the validate button to validate the required permissions.

Step 6. The software provides three ways to add users from the source account. Use any of them to add users to the software panel.

  • Fetch Users – It automatically fetches users from Source.
  • Import Users – It imports users through CSV.
  • Download Template – It downloads a template to be used as a sample for creating a CSV file.

Step 7. Select the required PST files provide the destination user Email accounts and validate permissions. Click on the start import button to import PST to Office 365 without duplicates.


Method 3. Using Network Upload to Import PST to Office 365 

Network upload is a manual way to import PST to Office 365 without duplicates. On a cloud, the user has to add PST files through the network. Although it is an effective method but slightly complicated and lengthy to run. The user will need Azure AzCopy software for this purpose and then proceed further.

Also Read: Migrate Distribution Group to Office 365 Safely – Comprehensive Guide

Method 4. Import PST to Office 365 Without Duplicating Using Drive Shipping

Another method to migrate PST files to Office 365 skip duplicates is by physically shipping the files to Microsoft’s Data Center. However, it is important to note that this manual approach is time-consuming and expensive.

Here is a proper explanation of the process:

Step 1. Copy the PST files that you want to migrate onto a hard drive.
Step 2. Encrypt the hard drive using BitLocker or any other encryption method to ensure the security of the data during transportation.
Step 3. Package the hard drive securely to protect it from any damage during shipping.
Step 4. Contact Microsoft’s Data Center or the designated address provided by Microsoft for physical data migration.
Step 5. Follow the instructions provided by Microsoft for shipping the hard drive to their Data Center. This may involve generating shipping labels, providing relevant information, and complying with any specific requirements.
Step 6. Send the package containing the encrypted hard drive to the designated address using a reliable shipping service.
Step 7. Once Microsoft receives the package, they will handle the process of extracting the PST files from the hard drive and importing them into your Office 365 account.
Step 8. After the migration process is complete, Microsoft will notify you of the status and provide any necessary information or reports regarding the migration.

It’s important to consider the potential drawbacks of this method, such as the time it takes for physical shipping, the cost associated with shipping and handling, and the risk of damage or loss during transportation. Additionally, this approach may not be suitable for urgent or time-sensitive migrations.

While this method provides an alternative for PST migration, it is generally recommended for cases where other options are not feasible or practical. It’s advisable to assess the specific requirements and constraints of your migration project before deciding on this manual approach.

For info about Drive Sipping refer to this article:

Pitfalls of Manual Methods In Importing PST Files to Office 365 Without Duplicates

While manual methods to import PST files to Office 365 without duplicates may seem like an option, there are several pitfalls to consider:

  • Manual methods involve multiple steps and processes, which becomes complex and time-consuming. Especially when dealing with large PST files or a significant number of mailboxes. It requires manual effort, which results in overall delays in the process.
  • As the manual method is being performed by users, hence, they are prone to human errors, such as selecting incorrect folders, missing files, or encountering issues during the migration process. These errors can lead to data loss, duplicates, or corruption of the migrated data.
  • They also lack in providing automation capabilities. Which requires users to perform repetitive tasks individually. This increases the chances of mistakes and makes the overall process less efficient.
  • It is evident that these methods are not suitable for organizations with a large number of mailboxes or complex migration requirements. As, handling multiple PST files manually can become overwhelming, leading to inefficiencies and potential errors.
  • Users can not enjoy features such as deduplication, email filtering, or handling complex folder structures, as the manual methods do not comprise any of them. These features are crucial for a smooth migration process and for maintaining data integrity.
  • Physically shipping PST files to Microsoft’s Data Center, as mentioned in a previous method, introduces security risks during transportation. There is a possibility of data breaches, loss, or damage to the physical storage media.
  • Users can not get comprehensive reporting and monitoring using manual methods. Which makes it difficult to track the progress of the migration or identify any issues that may arise during the process.

Considering these pitfalls, it is recommended to use professional software or third-party migration tools that offer automation, advanced features, scalability, and data security. These tools are specifically designed to streamline the migration process, minimize errors, and ensure a successful and efficient transition to Office 365.

Must Read: How to Import PST to Outlook 365 Web In Few Steps? Everything You Need to Know


After analyzing all the ways to import PST to Office 365 without duplicates, the manual methods seem to be quite complicated and for a naive user, it can be pretty difficult to adopt these manual techniques. Moreover, the manual method has its limitations and shortcomings.

On the other hand, the above tool seems to be a sophisticated and safer solution to import PST to Office 365 without duplicates instantly. Now, it is up to the user, what they use, but they must be aware of losing crucial data if they follow the manual method.