MS Outlook is a popular business email client used by enterprises across the globe. Outlook, when configured with MS Exchange Server in Cached Exchange Mode, creates and stores a synchronized copy of mailbox data, such as emails, attachments, contacts, notes, etc., in a local OST or Offline Folder file.

The OST file allows Outlook users to access their emails and work offline even when the server is under maintenance or the system is not connected to the internet. However, when an OST file becomes inaccessible due to synchronization errors, system crashes, malware or virus intrusion, etc., you can’t access your emails or Outlook profile. Similarly, if your Outlook profile is disabled or deleted from the Exchange server, the OST file enters the orphaned stage and becomes inaccessible.

An OST to PST converter software, such as Stellar Converter for OST, comes in handy in such situations. The software can help you restore your mailbox items from inaccessible or orphaned OST files to PST.

In this post, we’ll review Stellar Converter for OST, a powerful OST to PST converter software to convert and migrate mailboxes from inaccessible and orphaned OST files to PST and other portable file formats.

Stellar Converter for OST – An Overview

Stellar Converter for OST is a highly recommended professional software by MVPs and IT administrators to convert Outlook OST files to PST format. The software helps Exchange users and IT administrators migrate mailbox items from OST file to PST or another existing Outlook profile, live Exchange server, or Office 365 tenant directly. The software also scans and recovers deleted mail items from Outlook OST files.

Admins and Outlook users can use the software to fix common Outlook OST errors, such as Send/Receive errors, by exporting the mailbox items from OST to Outlook importable PST file format.

Further, the software can also convert password-protected or encrypted OST files. Besides PST, you can save the mail items in EML, PDF, RTF, MSG, MBOX, DBX, and HTML format.

Key Features

Stellar Converter for OST is available in two editions – Corporate and Technician. Following are some key features of Stellar Converter for OST software.

Corporate Edition

  • 3-step OST to PST conversion – Scan, Preview, and Save
  • Converts orphaned or inaccessible OST files to PST
  • Converts large-sized OST files without file size limitation
  • Extracts mailbox items from encrypted OST to PST
  • Displays enhanced preview of mailbox items before saving
  • Multiple saving options, such as EML, PDF, RTF, MSG, and HTML
  • Option to sort and filter mailbox items for specific email or mail item recovery
  • Provides an option to save scan and load scan to resume OST to PST conversion later
  • Supports Outlook 2007, 2010, 2013, 2016, 2019, and Office 365

Technician Edition

In addition to all the features available in Corporate edition, the Technician edition also offers the following features:

  • Converts multiple OSTs simultaneously to corresponding PSTs
  • Directly exports mailbox data from OST file to Office 365 or live Exchange server
  • Converts OST mail items to DBX and MBOX formats
  • Compacts large OST mailbox into compressed PST file
  • Directly exports Contacts to CSV format
  • Splits and saves large OST mailbox into multiple PST files to avoid corruption

Pricing and Plans

  • Stellar Converter for OST – Corporate ($79/year)
  • Stellar Converter for OST – Technician ($149/year)

Both are available in a free demo version that enables you to scan and preview the OST file. It also allows you to save 20 items per folder for evaluation purposes.


Stellar Converter for OST requires a system that meets the following minimum software and hardware requirements:

  • Operating System: Windows 10, 8.1, 8, and 7 (64-bit or 32-bit)
  • Processor: Pentium class
  • RAM: 2 GB RAM (minimum)/4 GB (recommended)
  • Storage: 250 MB

The performance of Stellar Converter for OST software may vary based on system hardware and OST file size. However, the software is highly optimized to run on any system that meets the minimum system requirements mentioned above.

Read this OST to PST converter software benchmark study to know more about Stellar Converter for OST performance.

How to Use Stellar Converter for OST?

To convert OST to PST format or migrate mailbox items from an inaccessible OST to Outlook profile, live Exchange Server, or Office 365, follow these steps:

Step 1: Download and Install Stellar Converter for OST

Stellar Converter for OST – Corporate and Technician editions are free to download. The free demo editions of the software allow you to convert and save up to 20 mail items per folder. You must activate the software to save more mailbox items from OST file to PST or other formats.

The installation is quick. After downloading the program file, launch it and follow the installation wizard. The software supports English, German, French, Spanish, and Italian languages, which you can choose during or after installation.

Stellar Converter for OST

Step 2: Scan OST File

  • After installation, launch the software and click Browse to choose the OST file. Use the Find button to search and select the OST file for conversion. Click ‘Convert‘ to start the OST scan process.

Scan OST File

Step 3: Preview OST Mailbox Items

  • After the scan, click on a mailbox folder or email item to see its detailed preview.

Preview OST Mailbox Items

  • The software highlights deleted mailbox items. This helps to quickly find and recover deleted mail items.
  • You can use the Find Message to find specific mail items using parameters, such as To, From, Subject, Attachments, Body, Date, etc.

stellar find message

  • You can also click Save Scan under the Home menu to save the OST scan information. This helps you load the scan information and resume OST conversion later without rescanning the OST file.

stellar Load Saved Scan

Step 4: Save OST Mailbox Items

  • Select the mailbox items you want to save or export to PST or live Exchange and Office 365. Then click ‘Save Converted File‘ under the ‘Home‘ menu. You must activate the software at this stage to continue.

Save OST Mailbox Items

  • After activation, choose PST or any other save option from the ‘Save As’ dialog box and check ‘Do not recover Deleted Items’ if you want to exclude them. Then click ‘Browse’ to choose a location and click ”

Live Exchange Server - save as

NOTE: To export mail items from OST file to Live Exchange Server, Existing Outlook Profile, or Office 365 directly or convert multiple OST files to PST, install Stellar Converter for OST – Technician edition.  


Based on our tests, we found that the software performs consistently and converts large OST files to PST. In addition, it recovers deleted mailbox items and restores mailbox items from inaccessible and orphaned OST files. We will recommend this tool to anyone who is looking for an easy and quick solution to migrate mailbox items from OST to another Outlook profile, live Exchange Server, or Office 365 with 100% consistency and accuracy.

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