Free Methods to Import OST to Microsoft 365

Summary: If you are a regular Outlook user then you must be using IMAP and Exchange accounts on Outlook which by default helps to store the data in an .OST format.

To import OST to Microsoft 365 account easily. This blog will help to discover the methods through which it can be done.

Microsoft 365 has become the top-most cloud service provided by Microsoft. It has hundreds of millions of users worldwide. It has been able to offer a flexible platform to work in a diverse environment. However, at times there may be need to migrate the mailboxes from Outlook of on-premises Exchange to Office 365. All of this process may require you to convert an OST file into PST File.

When the users want to migrate from on-premises Exchange to Microsoft 365, then they need to extract the data from of the OST Files as Office 365 does not support the data in OST file format . The Offline Data File (OST file) is the replica of the Exchange mailbox data while the online data file (PST file) contains the important emails, contacts, notes, sent items, attachments, calendar details, etc.

Whenever the connection between Outlook and Exchange Server is down, it is still possible to access the data on Outlook with the help of this offline tool. Therefore, importing OST to Outlook 365 gains importance. While following these methods, it is essential to take proper care of the methods because there is a possibility that the manual steps may not work as per the expectations and the business community may be disrupted for a while.

Need for importing OST to Office 365

There are many advantages of the Exchange mailbox data on a cloud platform like Office 365. If you have the internet connectivity, you can access all emails in Office 365 from any computer any place. Many Exchange users want to keep a copy of their Exchange mailboxes on Office 365. To facilitate this, one can move their Offline Outlook Data File (OST) to Office 365 accounts and this can be done in many ways.

Before that, there are some causes which tend users to move their OST files to Office 365.

  • Preventing Exchange crash and for a reliable platform.
  • Organizational shift owing to Office 365 advantages.
  • Quick access of data in safe environment after accidental deletion.
  • To avoid big Exchange maintenance downtime and save the time and money.

In the present article, we will discuss the manual methodologies to import OST to Microsoft 365. There is no direct method to place your OST files directly to your Microsoft 365 accounts. The user has to create some workaround strategies to convert and import/export the data.

1st Method: Convert OST file to PST and Import PST to Microsoft 365

The first manual method is an indirect method where you can convert the OST files data to PST and then import the PST file to Microsoft 365 because Security & Compliance of Microsoft 365 supports the import job of PST files.

Here are the steps to create the PST files;

  1. Start Outlook and click File option.
  2. Go to Open & Export and click Import/Export wizard.
  3. After opening the Import/Export wizard, choose the option ‘Export to a file.’ Click on ‘Next’ option.
  4. Select the second option ‘Outlook Data File (.pst)’ and click Next. Select the mail account or choose individual mailboxes, such as ‘Inbox’ or ‘Sent Items’ to export them (select one item at a time).
  5. The wizard will present you all the folders of the Outlook OST mailbox account. Check the option Include Subfolders and click Next.
  6. Click the Browse button to mention the location of the PST file. Then click Finish.
  7. A new PST file has been created including all the data of your OST mailbox account.
  8. Note: One cannot migrate OST file data like message rules, folder properties custom views, meeting schedules, etc. using the above method.

The second process requires you to import the PST files to the Microsoft 365 using either the Network Upload or Drive Shipping methods.

Note: It is crucial to activate the Mailbox Import Export role to the Microsoft 365 mailboxes before starting the process. For that, log-in to the Exchange Admin Center of the account, go to Permissions and open Organization Management by double-clicking the mouse. Click on Add option and then add the Mailbox import-export role and click on Save finally to save it.

Network Upload Method

The Network Upload method helps you to migrate multiple PST files at the same time. We are providing you the steps of the method in a precise manner;

  1. Download the AzCopy tool and get the SAS URL of your organization: The AzCopy tool is required to run the network upload method and the SAS URL is a collective URL of the network URL of Azure Storage location and Shared Access Signature Key.
    1. Login to or your organization with the help of Administrator credentials.
    2. At the Security & Compliance Center, choose the option to Import PST files and click New Import Job.
    3. Choose the first option to Upload your data.
    4. The next page will ask you to Copy the SAS URL for network upload and use the AzCopy tool to upload the PST files.
  2. Use AzCopy tool to upload PST files to Microsoft 365: The AzCopy tool uploads the PST files directly to the Azure Storage location of your organization.
    1. Open the command prompt as the Administrator.
    2. Go to the folder location where you have installed the AzCopy Tool and run the command –
      AzCopy.exe /Source:UNC-Path-of-PST-File /Dest: /V: /Y
    3. Note: Enter the PST file (to be uploaded) path and the SAS URL copied earlier in the previous section.

  3. Create Import Mapping File: After you have saved the PST files at the Azure Storage Location, you need to create a comma-separated-value (CSV) file that will have the name and details of the Microsoft 365 mailboxes that will have to save the PST files. You can create the CSV file by mentioning various properties like workload, FilePath, Name, Mailbox, TargetRootFolder, ContentCodePage, etc.
  4. Create a new Import job for PST files: You again need to go to the Security & Compliance center at Microsoft 365 Admin Center and choose the option New Import Job.
    1. Choose the option ‘Upload your data.’
    2. Click the checkbox the two options – I’m done uploading my files and I have access to a mapping file.
    3. Click the Select Mapping File button and upload the earlier created CSV file.
    4. Click the Validate button to verify the content of CSV files.
    5. Click Save to submit a job.
  5. Start the PST Import Job and filter the data: The new Import Job will check the selected data and allow you to filter the data from the PST file. After making all the changes, start the migration.
Drive Shipping method

Drive Shipping method saves you from the long and tiresome procedure of the network upload method. If you choose the Drive shipping method, you only need to create the PST files copy these files to Drive and contact Microsoft. A Microsoft Official will collect the PST file from you or you can ship the drive to Microsoft Office from your end and upload it to the Microsoft 365 mailbox. But this process is also not suggested mostly as it would take about 10 days to ship the PST file from PST to Office 365 via Microsoft official.

2nd Method: Use a Professional software

Professional OST to PST converter software is your option to conduct any migration towards Microsoft 365. It does not require any lengthy procedure or prerequisites but only the data from the PST files and the credentials of your Microsoft 365 account only. You can purchase any suitable software that has all the advantages of the migration.

Our recommendation is the most efficient Best OST to PST Converter software to migrate OST or PST files to Cloud platform directly and securely. Visit the tool website to get completion details about its features. Get started for the exclusive migration!


It is only with the help of all of these methods which are free to use, that it becomes feasible to import OST to Microsoft 365. These methods are very easy to execute and do not require any much of the effort. All of these methods are extremely useful from the viewpoint of the user.

About Elias Macclure

Elias has a sleek writing style, and the reader may find that the extensive nuances of the material are covered in the article. He changes the writing style according to the platform and writes fine for Office 365 and SharePoint. He is an active reader and reads books by renowned writers including Charles Dickens, Sidney Sheldon and Agatha Christie.


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  2. Try the manual method to convert OST file to PST file format and then by using Drive Shipping method, you can easily import PST to Office 365 mailbox. It’s a lengthy process but you can also try third party tool like I did to export OST file directly to Office 365 account in quick manner.

  3. This is one of the best manual methods to import OST to Microsoft 365. During my first attempt to use this manual method, I took a little extra time to import OST to Office 365. You will succeed in completing your task if you follow the procedure step by step. 

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  6. This blog guided me through the process of uploading an OST file to Office 365. I had some difficulties with the first method’s application at first, but after following the instructions in the blog, I was able to achieve a satisfactory result. It is an excellent article on exporting OST to Office 365.

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  8. There are many methods to import OST Emails into office 365, but I am not satisfied with that method, they was creating lots of problems with a doing conversion, then I used above recommended software and apply the given methods and after few minutes my OST files easily imported in office 365.

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  14. To export my OST data to Microsoft 365, I used these free manual methods. Those methods are describe in continuous steps and saved my OST file in this Office 365. Amazing methods.

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