Microsoft Outlook stores mailbox data in two file formats: OST (Offline Storage Table) and PST (Personal Storage Table). OST files allow users to work offline and sync later with the Exchange or IMAP server. But problems arise when OST files become orphaned, inaccessible, encrypted, or corrupted, often after a mailbox is deleted, the Exchange server crashes, or Outlook fails to sync. In such cases, OST files can no longer be opened directly in Outlook.
That’s where Stellar OST to PST Converter comes in. It is a professional tool designed to extract mailbox data from inaccessible OST files and convert them into PST or other usable formats. In this review, I’ll cover how the tool works, its features, performance, and whether it’s worth recommending to end users and IT admins.
Stellar OST to PST Converter
Stellar OST to PST Converter is essentially a data recovery and migration utility. It:
- Converts inaccessible, orphaned, or encrypted OST files to PST with 100% data integrity.
- Supports recovery and conversion of all mailbox items: emails, attachments, calendars, contacts, notes, tasks, journals, and deleted items.
- Provides multiple output formats: PST, MSG, EML, RTF, HTML, and PDF for broad compatibility.
- Batch conversion: Convert multiple OST files at once, crucial for business/IT group mailbox management.
- Fast, reliable performance—handles large files and complex mailboxes without compromising speed or security.
- Preview feature for mailbox content before export allows selective item or folder recovery and conversion.
- Technician Edition allows splitting and compacting PST files, saving storage space, and improving Outlook stability.
- Supports exporting directly to Outlook profiles, Exchange Server, or Microsoft 365/Office 365 (Technician edition).
In short, it provides a way to recover mailbox data when OST is the only available source.
Key Use Cases
- Export OST to PST: If a user mailbox is deleted from Exchange/Active Directory but the OST file remains, Stellar can recover and convert it into a PST.
- Fix Offline OST Synchronization Errors: When Outlook fails to sync with Exchange and rebuilding the OST isn’t an option (e.g., mailbox deleted), the tool can extract mailbox items from the OST.
- Migrate OST to Office 365 / Microsoft 365: Useful for companies moving to the cloud. Even if Exchange is down or hacked, you can restore OST data directly into Microsoft 365.
- Handle Special Cases
- Works with large OST files (multi-GB).
- Converts encrypted OSTs to PST.
- Helps during Exchange crashes or migration projects.
Steps to Use the Stellar OST to PST Converter Tool
- Download and install the Stellar OST to PST Converter Software on your system. Once installed, open the application to begin.
- A dialog box will appear with two options:
- List Profiles = automatically detects Outlook profiles configured on your system.
- Choose Manually = lets you browse your computer and select an OST file directly.
Pick the option that best suits your setup. If you’re choosing manually, your .ost files will be stored in this location: C:\Users\<YourUsername>\AppData\Local\Microsoft\Outlook\.
- After selecting the OST file, click Convert. The software will scan the file to retrieve mailbox data. The duration of this scan depends on the size of the OST file.
- Once scanning is complete, the tool displays a preview of your mailbox. You can browse through emails, attachments, contacts, calendars, tasks, and notes before exporting.
- Click Save Converted File. You can choose from multiple saving options, such as:
- PST (Personal Storage Table)
- Other formats like MSG, EML, RTF, PDF, HTML
- Click on Next.
- Select the desired format and location, then click OK. The conversion process will begin, and the new file will be saved at your chosen destination.
- If you exported to PST, open Outlook, go to File > Open & Export > Import/Export.
- Select the newly created PST file to access your recovered mailbox data, then choose Stellar Converter for OST, and click Finish.
That’s it! You can now open Outlook and access all your recovered emails. This is how you can use the Stellar OST to PST Converter to restore mailbox data.
Stellar OST to PST Converter Features
- Intuitive Interface: Select OST → Scan → Preview → Export.
- Preview Option: Lets you view all mailbox items before exporting.
- Filters & Selective Export: Export specific folders, dates, or items.
- Split PST Feature: Break large PSTs into smaller, manageable files.
- Deleted Item Recovery: Sometimes retrieves items marked as deleted within OST.
- Multiple Export Options: PST, MSG, EML, RTF, PDF, HTML.
- Save Scan State: Resume work without rescanning large files.
- Direct Migration: Export directly into Outlook profiles, Exchange, or Office 365 (Technician edition).
Performance & Reliability
In tests and third-party reviews:
- A 3 GB OST file was converted and exported in about 7–8 minutes.
- Folder hierarchy, attachments, metadata (From, To, Cc, Bcc, timestamps) were preserved.
- The tool handled large OST files efficiently without crashing.
- Encrypted OSTs were successfully converted.
User testimonials and MVP reviews generally confirm high reliability and precision, though real-world results may vary for severely corrupted files.
License and Pricing Details
The tool features several editions for different needs: Corporate for individuals, Technician for IT admins with advanced options, and Toolkit for larger enterprises. Licensing is straightforward, offering single-pay plans, annual updates, free trial, and responsive support.
Pricing varies by edition and may change over time. Instead of listing prices here, please refer to Stellar’s OST to PST Converter Software page for the most recent rates and licensing details.
Conclusion
Stellar Converter for OST proves to be a dependable, feature-rich solution for recovering and accessing data from inaccessible or orphaned OST files. It stands out for its accuracy, speed, and ability to handle large or encrypted mailboxes without compromising data integrity. Whether you’re an individual user retrieving old emails or an IT professional managing complex Exchange or Microsoft 365 environment, the tool delivers consistent, professional-grade results.
While the annual licensing model and demo restrictions may be limiting for occasional users, the software’s advanced functionality, ease of use, and direct Office 365/Exchange export options make it one of the most comprehensive tools in its class.
Recommendation:
If you frequently work with Outlook or Exchange environments—whether for OST to PST conversion, OST to Office 365 migration, or troubleshooting—Stellar Converter for OST is a worthwhile long-term investment. For organizations and IT teams, the Technician or Toolkit editions add even greater flexibility with advanced export, splitting, and compaction features.
For one-time conversion scenarios, starting with the free demo version is the best way to validate its effectiveness before committing to a license.
After working for more than 18 years in Microsoft technologies like SharePoint, Microsoft 365, and Power Platform (Power Apps, Power Automate, and Power BI), I thought will share my SharePoint expertise knowledge with the world. Our audiences are from the United States, Canada, the United Kingdom, Australia, New Zealand, etc. For my expertise knowledge and SharePoint tutorials, Microsoft has been awarded a Microsoft SharePoint MVP (12 times). I have also worked in companies like HP, TCS, KPIT, etc.
