Import offline OST to Office 365

Updated On - May 27, 2023 by Armaan |

Reading Time: 5 minutes

With Exchange Online, businesses can benefit from Exchange Server’s advanced features without installing the server on-premises. Exchange Online can be accessed by those who subscribe to Microsoft 365’s Business or Enterprise Editions, which both include the service. The ability to purchase licenses for the number of expected users is a great perk of a Microsoft 365 subscription. It is available for purchase separately or as part of Microsoft 365, where it features full integration with the rest of Microsoft Office.

You may get confused because you can open an Outlook account in Office 365 and get all your OST file data to Office 365. OST is Microsoft Outlook’s file format used to store data on the server. However, with Office 365 trend, and Office 365 including Outlook, users want to import their old OST files to Office 365. But what if the OST files are corrupt and offline? How will you import offline OST to Office 365?

In this write-up, we’ll look for the same, but before that, let’s identify the scenarios which raise the need to import Offline OSTs.

Why is there a need to import Offline OST to Office 365

Having Outlook OST files in the cloud can provide several benefits; you can access OST file data at any and anytime. We all know Office 365 is a cloud platform accessible worldwide and on any device such as Mac, iPhone, Android, or Desktop, you name it.

Apart from this, there can be several scenarios for which you may need to import Offline OST to Office 365, such as:

  • Your organization have moved to the Cloud server, and you want to keep your data.
  • Some of your colleagues or clients use Office 365 with whom you need to share your Offline OST files data.
  • Also, by moving your OST to Office 365, you can replace your server’s hosting and maintenance charges, as Office 365 is cloud-based and doesn’t need any installation.
  • Also, office 365 allows you to access your device on multiple devices simultaneously. So it is a good move to import offline OST to Office 365.
  • Last but not least, almost every office 365 user who has shifted from Outlook has admitted that Office 365 is more convenient and advanced than Outlook.

Now you’re aware of the scenarios and benefits for which you might need to import your Offline OST to your Office 365 mailbox. Now move to our main heading of the article, which is how to take your OST files (Orphaned and corrupt) to Office 365.

Ways to import Offline OST to Office 365

The OST files must be converted to the PST format first. At that point, we transfer the PST files to Office 365. After converting OST files to PST format and uploading them to Office 365. This is a roundabout approach to importing OST files into Office 365.

Phase 1: Change the File Format from OST To PST.

  1. Launch the Outlook email client. Navigate to “File” and then “Import and Export.”
  2. Click “Export to a file” and then “Next” to export the data to a file.
  3. When prompted, select “Personal Folder File (.pst)” and then “Next.”
  4. Click “Include Subfolder,” choose the email or folder, and then “Next.”
  5. Select a destination on your computer’s hard drive, tick the box labelled “Replace duplicate with items imported,” and press “Next.”
  6. You can enter a password (if you choose) or just click “Ok.”

Please note that the stated method will not work if the Exchange server is down or unable to connect to the server. So, if you need to convert OST files to PST format, utilize the Regain OST to PST converter; it has many benefits, which I’ll tell you in the end.

Phase2: Move your PSTs to the Office 365 cloud

  • To access Exchange after logging into Office 365, navigate to the Admin Center.
  • Now, double-click “Organization Management” under “Permissions.” a window labelled “Exchange Admin Center” (EMC) will load. When the new window opens, choose “Mailbox Import Export” by clicking the plus symbol. After selecting “Add,” confirm by selecting “Ok.”
  • Again, choose “Mailbox Import Export” and click “Save.”
  • Click “Upload file” under the “Admin Center,” “Setup,” “Data Migration,” and “Upload” menus.
  • Later, after naming the import job, select “New Import Job” and proceed from there.
  • Click “Upload Your Date” and “Next” to go to the next step.
  • Select “Show Network Upload SAS URL in the new box,” then copy the URL and paste it into the notepad.
  • Acquire the Azure AzCopy here. When you click “Run,” the programme is automatically set up.
  • To import a PST file into Office 365, you must first allow access to the folder or file in question and then copy its Network Path.
  • Open the Microsoft Azure AzCopy tool and type: AzCopy.exe /Source: Network Path or File location /Dest: “SAS URL”/V: location path where you wish to save the log file /AzCopy.log /Y,

Sample Code:AzCopy.exe /Source:\DESKTOP-MPKVU38UsersleDesktopImport /Dest:”” /V:c:UsersleDesktopAzCopy.log /Y

  • Once the PST file has been uploaded to the mailbox account, a CSV file will need to be created to map the PST file into the mailbox account.
  • Click “Next” in the import data window after checking both boxes.
  • Select “Upload CSV file,” then “Validate,” then “Save,” and finally “, Select Mapping file.”

At last, your PST file will be successfully imported to Office 365. Hence, you’ve successfully import offline OST to Office 365.

Why not fall for the manual approach?

So it was the manual process to import your OST files into Microsoft 365 mailboxes. As you can see, the process is lengthy and may be a walk on eggshells. Apart from this, if you’ve multiple Offline OST files to import, don’t even think about it.

By using the above-mentioned tool, Regain OST to PST converter, you can directly import Offline OST files to Office 365.

Free Download100% Secure Buy NowPrice: $39

The tool effectively keeps your files hierarchy and Integrity with a 0% chance of data loss. Also, the tool offers a convenient GUI that makes it the best option for newbies and businesspersons. Let me describe its step-by-step process so you can install free software and check its features and compatibility with your scenario.

Import Offline OST to Office 365 in a few steps:

  1. Install and open the free OST importer tool.
  2. Click on the Open option from the ribbon bar.
  3. Now add OST files to import into Office 365.
  4. Click on the Cloud Migration option at the top.
  5. Choose Office 365/Exchange Server option.
  6. Now the tool starts to import Offline OST to Office 365.

As you can see, importing Offline OST files into Office 365 is a cakewalk with Regain OST to PST converter. So what are you waiting for?


With time, Technology changes as well. Nowadays, Outlook users are looking for an efficient way to import Offline OST to Office 365. For the same, I’ve mentioned two methods one is manual, and another one uses a third-party automated tool. Now it’s up to you what you choose. Remember, whatever you choose, choose according to your need and ease. You can click here to learn about Regain OST to PST converter’s feature.

Author: Armaan

Hello I have been working in Regain Software for the last 6 months. I have been in the field of writing for many years and worked with many Data recovery companies. Here I am writing technical blogs, Software User Guides and manual methods for email conversion and cloud migration. Now, working on all products of our company. Thanks you

One thought on “Import offline OST to Office 365”

  1. Avatar Hannah Johansen says:

    Great resource! I simply followed the procedures and was able to import my OST file into Office 365. Thank you for the detailed directions!

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