Import OST to Office 365- Best Known Migration Techniques of 2023

  •   Written By
  • Published on
    September 10th, 2021
  • Updated on
    January 28, 2023
  • Read Time
    6 minutes
4.7/5 - (4 votes)
Summary:-To Import OST file into Office 365 manually required proper management and planning. Sometimes, it also depends on the size of the mailboxes. OST file stands for Offline Outlook Data File(.ost) as it is used by multiple POP & IMAP-based accounts, Microsoft 365 accounts, Exchange server accounts, and accounts. It is mainly associated with these products and provides users offline access to data on their systems.

When your connection to the internet is not proper, or if it has been interrupted due to a network issue, you can still access your emails, calendar, contacts, and tasks stored previously. Here, you can also read and compose an email, schedule appointments, and add data. However, your messages and other data are timely and up-to-date while you establish the internet connection again.

An exchange server is a business-class collaboration utility that primarily focuses on sending, receiving, and storing email messages, and for this, it uses an OST file. It also allows their users to protect the OST file with a lock which means: those OST files don’t have the associated mailbox profile on Exchange, and there is unsaved data in the OST. Exchange mailbox stores files in such a way that they can’t be migrated into Microsoft 365 directly- however, there is a manual and professional way to import OST file into Office 365.

Where do We Need to Perform OST Files to Office 365 Migration?

Some causes tend users move their OST files to Office 365 environment are:

  • If your Exchange mailbox data is on a cloud platform such as Office 365 has many benefits.
  • Message on Office 365 is accessible universally, and the need is only to establish the proper internet connection.
  • Sometimes, users want to store a copy of Exchange server data in Office 365.
  • Users are looking for a solution to export OST file data into office 365 to access it online.
  • The possibility that the Exchange gets crashed and needs a reliable platform.
  • Avert running the Exchange maintenance downtime process.
  • To access and work with data in a safe & reliable environment.

Read here: Difference Between OST and PST l What Is OST & PST Files?

Methods to Import OST File into Office 365 Manually

There is no particular way to migrate OST files to Office 365, yet you can convert OST to PST and add them into Office 365. It is an indirect method that involves two steps:

  • Convert OST Into PST Format
  • Import PST Files into Office 365 Account

Step 1: Convert OST Files to PST format

  1. Launch Outlook and click on the File menu.
  2. Go to the Open & Import and select the Import/Export section.
  3. Select the option: Export to a file and click on the Next button.
  4. Choose Outlook Data File(.pst) from the drop-down and tap Next.
  5. Here, you have to pick the emails or the folder and check the Include subfolders option. Click Next.
  6. Select the Browse button to add the saving location to download PST.
  7. Opt with inbuilt features if necessary to remove duplicate emails and click the Finish button.
  8. Set the password on the PST file, if you want.
  9. Finally, click on the Ok button to export the PST file.

Step 2: Add the PST File To Microsoft 365

After transferring the OST file to PST format, Now you need to import PST files to Office 365 in multiple ways.

  • Using Azure AzCopy.
  • Using Drive shipping.

Upload PST File to Office 365 Using Azure AzCopy

  1. Firstly, download and install the Azure AzCopy.
  2. Complete the installation procedure and copy the Shared Access Signature(SAS) URL to provide permission for migrating the PST file to Azure.
  3. Now, upload the PST into Office 365 and create a PST to map(.csv)
  4. You will also have to create an import job in Outlook 365 to add PST.
  5. Lastly, set a filter of data and begin the PST migrating process into Office 365.

Note:- Azure AzCopy is the type of method facilitated by the cloud platform of Microsoft that is respective from Office 365. Thus, you will have to implement some prerequisites before beginning the uploading process.

  • You will have to assign an Import Export role in Office 365 to implement the process. Here, the Administrator will permit access or by the management of the Role group.
  • An upload option is only available in the network upload method, and you will not be able to do so directly.
  • PST should be present in the network-shared folder. If not, then the utility is unable to access the folder.
  • Not supports the addition of the large-sized PST(limitation 20 GB)
  • Once the process gets completed, you will have to re-change the retention policy of Office 365. It will suggest this because there is a possibility that the incoming emails are older, and the system is unable to detect and remove them instantly.

Import PST File in Office 365 Using Drive shipping

Drive Shipping is another way to import OST File into Office 365. The need is to copy the PST files to the hard disk drive and upload it to Microsoft. Microsoft is one of the top-rated product provider companies that contains a feature to add data from a disk drive to Microsoft 365.

Method 2: Import OST files to Office 365 Professionally

It is the direct and easy method to import OST files into Office 365 accounts. This method will help you to export all the data from the Offline Outlook data .ost file to Office 365 in a few steps. This solution, OST to Office 365 Migration Tool is competent enough to import OST files into Gmail, Thunderbird, AOL, and other web & cloud-based email applications.

Step-By-Step Guide to Migrate OST files into Office 365

  • Download and Start the SysInfo OST to Office 365 Migration software.
  • Select the Single File or Multiple File/Folder options to add OST.
  • Choose the folders from the tree and preview mail & their attachments.
  • Opt with Gmail from the dropdown menu and Sign In with credentials.
  • Check the options required and click the Convert button.
  • Finally, you will import your OST file data into Office 365.


In this blog post, we discuss the manual solution to import OST files into Office 365. But due to complications of manual methods (firstly, convert OST to PST files and then import it to Office 365), the professional solution is the best and simple choice to perform the conversion.

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