How I Managed to Import an OST File into Office 365 (After a Few Failed Attempts)

I didn’t expect this to be as confusing as it turned out to be.

All I wanted was to move some old Outlook data into Office 365. Simple, right? But the moment I tried importing an OST file directly, I realized Outlook just doesn’t allow that.

After digging around and trying a couple of things that didn’t work, I finally found a method that did. Sharing it here in case it saves someone else the same headache.

Why Migrate OST Files to Office 365?

Before we dive into the steps, let’s take a moment to understand why this task is important. OST files (Offline Storage Table) are used by Microsoft Outlook to store emails, calendar entries, and other data offline. These files are essential for users who want to access their Outlook data without an active internet connection.

Moving that data into Office 365, which is the cloud-based version of Microsoft’s Outlook and other services, is necessary for many reasons, including data backup, improved accessibility, and using cloud features like shared calendars and collaboration tools. However, the transition isn’t always seamless, especially when working with older data stored in OST files. Office 365 doesn’t support direct import of OST files, which is why understanding the correct steps is crucial.

Complete Step-by-Step Process to Import OST Files to Office 365

Let's start, how I Imported my OST files to Office 365. Go through the stages and stepwise process given below and get your emails in Office 365 safely:

Stage 1: Convert OST to PST

If your OST file is linked to an account configured in Outlook, then you can just use the Import & Export feature to export OST email to PST. But if it is orphaned, you need a professional converter to do so. Here is how to convert OST file of an already configured account:

1. Open Microsoft Outlook, tap on File, then Open & Export, then Import/Export.
2. Select Export to a file and click Next.
3. Choose Outlook Data File (.pst) and click Next.
4. Select the folder containing imported MSG emails. Click Next.
5. Choose the saving location and create the new PST file. Click Finish.

All your OST data is now in the PST file.

Stage 2. Import PST file in Office 365 Account

Once you have the OST email in PST, configure your Office 365 account in Outlook and import the PST file. After configuring your Office 365 account in Outlook, follow the steps given below:

1. Go to the File tab and click on the Import/Export option.
2. Select Import from another program or file. Click Next.
3. Choose Outlook Data File (.pst). Click Next.
4. Click Browse and select the resultant PST file.
5. Select the options accordingly and tap on Next.
6. Check the folder, apply the filter and other options accordingly, and click Finish.
7. Your OST file email (now in resultant PST) import will be started. Wait for a few minutes.

Note: The Outlook Import & Export method is for a small amount of data or smaller file sizes. For large Email Migration, you can use the Office 365 Network Upload method to upload the PST file to Azure Storage.

Some Challenges of Manual Methods

However, the above methods to import OST to Office 365 are quite effective, but only administrators can perform them well. But there are also some other limitations and drawbacks, such as:

• Complex for bulk OST import to Office 365
• The process may be disrupted due to many factors.
• Chance of error may be there, as it is more complex.
• Probable chance of your important data loss.

Wrapping it Up

Migrating OST files to Office 365 isn’t as simple as a few clicks, but with the right process, it can be done. While using Outlook’s Import/Export method is great for smaller data sizes, administrators should consider the Network Upload Method for bulk migrations.

I hope this step-by-step guide helps you navigate the process of importing your OST files into Office 365 with less frustration. Whether you're a casual user or an administrator, the right approach will ensure that your emails are safely transferred to the cloud, making them more accessible and secure.

Good luck with your migration! If you run into any challenges, don’t hesitate to look for additional resources or reach out for more help.