Introduction:
An OST (Outlook Offline Storage Table) file is an offline data file used by Microsoft Outlook (a popular email client). OST files are associated with Microsoft Exchange server, Outlook.com, IMAP Server and O365. These (. ost) files are crucial in managing and storing email data like emails, contacts, and calendar items. These encrypted files make it possible for the user to work offline, making it a valuable resource for professionals and individuals.
On the other hand, PST (Personal Storage Table) files are used for storing and archiving data locally. The first and foremost advantage of using PST files is to reduce the amount of data residing on email servers. These files reduce the crucial time that system administrators have to spend helping end-users who have reached the maximum capacity of their inbox.
Sometimes we need to convert OST to PST files for different reasons like migration to a new system, accessing the data locked inside the OST file, switching email clients and others. For such conversion, you can use manual methods or by using OST PST Conversion Tools. This post revolves around how to import OST files into Microsoft Outlook step by step, so that you can easily access your mailbox data.
Why we need to convert OST to PST format?
Converting Offline Storage Table (OST) to Personal Storage Table (PST) is required for many reasons, and it is often done in the context of Microsoft Outlook. Below are some of the reasons why it may become necessary to import OST into PST.
- System Migration: One of the basic reasons why we need to convert OST to PST is migration to a new computer. The requirement arises when we need to transfer our old email data to the new system. In addition to this, importing an OST file may be required in cases like data recovery, mailbox migration, etc.
- Exchange Server Crash: In the case of an Exchange Server crash or Exchange Server maintenance, you will not be able to access your mailbox content. In such a scenario, converting OST to PST can be a way to recover and access your mailbox data.
- Deleted Items Recovery: We need to convert OST to PST to restore email or other data from Outlook that was deleted earlier owing to certain reasons.
- Mailbox Corruption: Sometimes, while working in Outlook, we might come across an error like ‘Can’t access Outlook data file(.ost).’ When such a message pops up, importing the OST file can help you get your mailbox data back.
- Moving to a New Email: If you’re considering using an email program other than Microsoft Outlook, you can change the OST file to PST format and then bring it into your new email client.
Methods to Import OST file to Outlook
First, we need to convert the OST files into PST format. Once it is done, we can go ahead to import the PST files into Outlook. We can import manually using Outlook’s Import/Export wizard. This method is recommended when large data files are not involved or user can still have access of their online mailbox. We can also use specialized OST PST Conversion Tool like Stellar Converter for OST to convert inaccessible OST file to PST format.
Method 1: Manual Methods to convert OST file
Use Import/Export method: This method uses Outlook’s built-in features, such as the Import/Export wizard, to export Outlook mailbox data to PST, CSV and ICS formats. With this approach, you can choose “Import from another program or file,” select the OST file, and follow the on-screen instructions. Even though the manual method suits everyone, but it is time consuming and less efficient when large or complex data sets are involved.
Following steps are involved in it:
- Launch the Outlook: Launch Microsoft Outlook on your computer.
- Access the Import/Export Wizard: Navigate to the “File” menu or “Open & Export” in the case of Outlook 2013 and later versions, and select “Import/Export.”

- Choose Export to a File: In the Import and Export Wizard, select “Export to a file” and click “Next.”

- Choose the desired file formats: Choose “Outlook Data File (.pst)” or CSV format as the file type to export to and click “Next.”

Under Export Outlook Data file: Select the folders you want to export in the desired file formats such as PST & CSV.
Choose the Destination for the PST File: Specify where you want to save the PST file. You can select an existing PST file or create a new one.
Specify Options: Depending on your preferences, you can select options for the export process, such as whether to include subfolders, how to handle duplicates, and whether to set a password for the PST file.
Start the Conversion: Click “Finish” to initiate the conversion process. You may be prompted to enter a password if you set one in the previous step.
Wait for Completion: Outlook will export the mailbox data into a PST file or CSV file formats. Sometime it may time taken depends on the file size. A progress bar will typically show the conversion process.
Finish: Once the conversion is complete, you’ll receive a confirmation message, and the PST file is saved in the location you specified.
Method 2: Archive Method
The archive method is used to manage mailbox size. It doesn’t directly import an OST file into Outlook as the Import/Export method does. However, it’s a useful way to manage and store older email data while keeping your primary mailbox uncluttered.
Steps of Archive Method:
- Open the Outlook and go the “File” option.
- Go to the Info File > Info > Tools > Clean up old items

Read more, How to archive the mailbox items in Outlook different versions.
Limitations of Manual Method:
It only works when the user has access to their mailing server or Outlook account.
You cannot import the OST file data from the encrypted, inaccessible file.
Importing OST files to Outlook manually is a time-intensive process due to the need for hands-on effort and a series of steps
Risk of data loss or errors during the manual import process
Handling extensive or complex OST files can be challenging manually
Manual methods to Import OST file to Outlook lack the automation and efficiency of software solutions
Method 3: Software Methods
As the name suggests, this method leverages specialized OST PST conversion tools such as Stellar Converter for OST. The tool preferred when the OST file is in an inaccessible or orphaned state, huge set of data files are involved, need to recover the deleted items, export the OST data to Microsoft Outlook, Microsoft 365 & Live Exchange etc. The tool is convenient and timesaving; these tools are perfect for users who demand a hassle-free and reliable way to import their OST files into Outlook.
About the Stellar Converter for OST?
Stellar Converter for OST is a powerful and versatile tool designed to address the needs of IT professionals and administers. This specialized software offers a comprehensive solution for converting OST (Outlook Offline Storage Table) files into PST (Outlook Data File) format, streamlining data migration, recovery, and management tasks.
Benefits & Features of Stellar Converter for OST?
No File Size Limitations
Trusted by Millions of Users
Awarded by Top Tech Media
100% Safe & Secure to Use
Converts OST file in the multiple file formats (PST, MSG, RTF, EML, HTML & PDF)
Converts any file size of OST in the PSTs
Free preview of mailbox data after the conversion
Option to save the converted OST file in the DAT file format.
The software allows sorting and organizing of the emails by Date, From, To, Subject, Type, Attachment, Importance, etc.
Directly export the OST to PST converted files to Office 365/Outlook/Live Exchange.
Split & Compact PST file – to manage the large mailbox data
Supports Multiple File conversion
Conclusion:
In this article, we discussed different methods for the importing OST files into Outlook. Even though the manual methods are first choice to import OST files into Outlook for the simple but there are drawback in it that may lead to likelihood of errors. There may come a situation where you no longer have access to the Exchange server or if the OST files is corrupted or damaged. When such condition arise then you need a third party OST to PST converter like Stellar Converter for OST to export and open OST Files in Outlook. You always have the option of going to Stellar Converter for OST for a successful repair.