OST to PST Converter for Corrupt &Inaccessible OST Files

In short:Stuck with an orphaned or corrupted OST and no Outlook? This tool recovers your mailbox in 4 steps—add file,scan,preview,convert. Works offline;no Exchange or MAPI errors.
Total Ratings:274- Average Rating:4.8 out of 5

Fix corrupted or orphaned OST files and export to PST,Office 365,Gmail,or MBOX. Use for migration,backup and archiving—supports Exchange OST repair and works offline without Outlook.

  • Scan the corrupted or orphaned OST recovery deeply
  • Successfully tested with 150GB+ ANSI and Unicode OST files during enterprise migrations—no lag
  • Migrate data into PST,MBOX,EML,MSG,Office 365,Gmail &more file formats
Softonic CleanCNET 4/5 StarsA+ Security

Supports Outlook 2021,2019,2016,2013,2010,2007,2003 &Office 365 OST Files

✔ Instant setup✓ Trusted by IT Professionals✔ 100% secure download✔ 100% Virus Free

Feature Highlights

  • Fixes All OST Errors

    Solve "Cannot open OST" and "Exchange sync issues" instantly.

  • 100% Data Integrity

    Original folder hierarchy and attachments stay intact.

  • Offline Conversion

    Convert OST to PST without connecting to Exchange Server.

  • Bulk Conversion

    Migrate multiple OST files to PST in a single batch.

ScreenshotsVideoStepsRequirements

Softaken OST to PST vs. Manual Outlook Method:Which is Safer?

See why manual export can be risky and time-consuming compared to a dedicated recovery workflow.

ScenarioManual Method (Outlook)Softaken Software
Data Risk❌ High (corruption chance)✅ Zero (safe workflow)
Outlook Required?❌ Yes✅ No
Orphaned/Offline Files❌ Not possible✅ Fully supported
Technical Skill❌ Expert required✅ Simple 3-step process

Facing OST File Errors or Data Loss? Here’s the Fix.

⚠ Common OST File Problems

  • Cannot open the OST file
  • Exchange server unavailable
  • Outlook sync errors
  • Orphaned or corrupted OST

✅ How This Tool Solves It

Data loss is scary. That’s why we built a deep-scan engine that looks into every sector of your OST file so not a single email is left behind. Recover your important emails even if your Exchange server is down or the OST is corrupted or orphaned. Fixes MAPI errorsand IMAP/Exchange synchronizationissues when Outlook won’t open the file. Unlike Scanpst.exe,this works on disconnected or inaccessible OST and exports to PST,MBOX,EML,or Office 365 and Gmail—with no data loss. Trusted in corporate settings.

When Do You Need an Inaccessible Mailbox Fix Tool?

Common scenarios where conversion becomes essential for data recovery and migration.

Tip:For OST files over 50GB,close Outlook before scanning for best performance.

OST File is Corrupted or Inaccessible

OST File is Corrupted or Inaccessible

Recover damaged or inaccessible OST files and convert orphaned OST to PST when the mailbox can’t be opened in Outlook.

Exchange Server Crash or Downtime

Exchange Server Crash or Downtime

When Exchange Server synchronization fails or the server is offline,the utility retrieves emails from the local OST.

Outlook Errors or Sync Issues

Outlook Errors or Sync Issues

Fix "OST file is not an Outlook data file"errorsand open OST without Outlook when the client won’t load the file.

Email Migration

Email Migration

Move your emails to Gmail,Office 365 and other platforms without hassle—no re-typing or manual export.

Backup and Archiving

Backup &Archiving

Tools create a safe backup of contacts,calendars and emails.

Switching System or Profile

Switching System or Profile

Safely transfer Outlook data to a different system or account

Who Should Use This OST Converter Tool?

This tool is designed for a variety of useful applications:

👨‍💻

IT Administrators

Manage Exchange recovery and mailbox data from OST files with ease.

🏢

Businesses

Convert emails to Office 365,Gmail or other platforms securely

👤

Individual Users

Easily access orphaned or corrupted OST files without Outlook.

📊

Professionals

Keep email backup,compliance and archiving on track—without extra tools.

Prominenet Features of Outlook Data Migration Software


Convert Files

There is no requirement to install MS Outlook to perform the conversion. Users can Open Outlook OST file without having Outlook. The software is independent to work alone and once OST file is scanned,the tool provides an instant preview of Offline OST items. From there,a user can right click on any message and save it in HTML/MHTML format to view any of the web browsers. Similarly,contacts are saved in vCard format and calendars in ICS format

multiple ost export options
Convert OST File to PST &Multiple Other Formats

This tool for OST to PST Conversion perfectly migrates all items inside the OST file like email messages,notes,contacts,tasks,etc. to PST format. Apart from this,you can use this app to export OST file to MBOX,MSG,PDF,EMLX,NSF,Office 365,HTML and TGZ. Without any inconvenience,the app exports OST mailbox data to these known formats in just a few clicks.

export selected ost folders

The OST File Exporter is easy to handle and there is no need of technical expertise to export Offline .ost file into .pst format. Users when load OST file and get preview of OST file. At that time,users are provided with options to export selective items or complete OST file into personal storage table format. Some simplified clicks are needed to perform the migration. Moreover,users will get these options separately to choose complete or desired folders from OST file for migration.

Encrypted and password protected ost file

There are no worries if you have a password protected Outlook data file. The OST to PST software works in a simplified manner and export complete mailbox items without any trouble. The users will not face any issues and any data harm while exporting OST file into PST format. 100% accuracy is maintained during the export process. Users can save the conversion results by creating a new PST file on their local system.

exclude empty folders
Exclude Empty Folders from large Sized OST Database

The users have full freedom to export any size OST file. Free OST to PST converter supports any large size OST file. Plus,users have the facility to exclude blank folders from the list of conversion. For this,the users need to enable 'ignore empty folders' option and this will not affect the folder hierarchy and you will find results after excluding empty folders. In this manner,extra items can be easily removed from OST file and hence the conversion task be performed without any extra efforts.

skip unwanted folders
Skip Unwanted Folders and Export Desired Database from OST

Once OST file is being scanned by the application,the users will get complete mailbox preview where all folders inside OST file are shown on the left side of the wizard. A user can tick mark required folders from there. In this way,a user can perform the required items conversion in a safe and quick manner without any hurdles. Plus,a user can save the exported items to their defined location without any disturbance and losses.

Preserve non english language
Preserve Original Language &Meta Data

Safety of data is one of the essential features during migration of OST files into PST format. The software takes care of it and perform the conversion in a proper way. It keeps all metadata items intact as original. To,cc,subject,bcc,attachments and the formatting applied to the emails are maintained properly. The original language of the data is duly preserved by the utility. Overall,security of data is on the topmost priority.

maintain folder Hierarchy
Maintain Folder Hierarchy in All Export Options

There will be no changes in the internal hierarchy of emails or folders while users convert .ost file into .pst and other formats provided by the tool. The application makes the conversion by organizing all data in a sequential manner as it was earlier before the conversion. No folder is missed and misplaced during the migration of offline storage table OST into PST format. You can say,the software is a trusted one app on which users can rely to export offline OST to PST format.

supported windows os
Support All Windows Operating Systems

The OST File Conversion software can be easily downloaded on all versions of Windows such as Windows XP,Vista,7 and higher versions. There is no effect on the processing by this tool even you are running other tasks in the background on your desktop. The application doesn't disturb other tasks and it will not affect the speed of the conversion.

supported outlook versions

Softaken OST to PST converter provides complete support to all major versions of MS Outlook. After successful conversion from OST file,a user can import PST file into MS Outlook 2019,2016,2013,2010,2007,2003. Without any trouble,you can read PST file on all editions of MS Outlook. The migration can be easily carried out in the absence of Microsoft Outlook and users can pick any file format to save OST file from the available formats.

advance filter
Deep Filtration options

Once PST file is loaded and display on the software screen,the users can pick items from OST file for conversion. Apart from that,users can filter the database more deeply with the Advanced filter options. Here,users can filter the database according to date range i.e. by specifying a start date and end date to export OST database to PST &multiple formats. Users can also filter the database according to subject,from,to,etc. and simply apply the filters. By these,the only required database can be exported from OST file.

extract email address
Extraction of email addresses

OST File Exporter is capable to extract only email addresses of multiple OST files at a time. A separate text file will be created to save email addresses of every OST file. The tool itself ignores duplicate email addresses of each file. There is an option 'include sent item folders' by which one can voluntarily include or exclude email addresses of sent folders. There is no damage and misplacement of any email address during the extraction process with this risk-free application.

extract attachments from ost
Extract attachments from multiple OST files

This offline folder recovery tool lets user to export multiple OST files so with this,users have the options to extract attachments from multiple OST files. All the selected OST files complete database or required database is exported by users as per their requirements. Moreover,the application works completely as per user instructions. The attachments and email formatting are well preserved and exported with OST emails in a risk-free manner. The users don't need to take tension of any loss and file misplacement with OST conversion program.

bulk ost conversion
Bulk OST files migration

Batch OST ConverterTool ensures that the conversion is performed under a safe roof. Using the folder mode,it is possible for users to convert multiple OST files in a single attempt. A user can export OST files of every size. Irrespective of file sizes,the utility deals with OST files of various sizes. There is no effect on the tool's performance due to the number of OST files. It's working efficiency remains the same whether you export single OST file or multiple OST files.

convert ost Calendars to ics

The application provides users the option to export calendars of OST files into ICS format. It is a universally accepted format for saving calendar entries. Apart from it,users can save calendars to MSG format to directly import OST calendars in MS Outlook. The MSG file having calendars can be simply imported to all MS Outlook editions. After providing the instructions to the application,it hardly takes few minutes to convert OST File calendars into ICS and MSG formats. In this manner,users can access OST file calendars to Thunderbird,Apple Mail,and other applications.

convert contacts in csv and msg

Softaken OST to PST file converter exports Address Book of OST into CSV and MSG formats. By exporting OST contacts into MSG format,these contacts can be easily imported to Microsoft Outlook application. Moreover,CSV file format is supported by various applications like Lotus Notes,Thunderbird,Apple Mail,Gmail,Yahoo,etc. In this way,OST contacts can be easily accessed on various platforms. Users can export unlimited contacts from OST file and with some clicks,the OST contacts are ready in CSV format whom they can access cloud-based and various desktop applications.

OST to PST Converter - Awards &Reviews

Expert recognition and trust signals for Softaken OST to PST Converter.

Verified:100% Secure Download

We take your data safety seriously. Softonic has thoroughly scanned our installer and confirmed it’s completely clean and safe for your system.

View Softonic Report

No Spyware,No Adware. Period.

Our tool is built for one job:conversion. Software Informer's expert editors have verified that there are no hidden trackers or annoying bundles included.

Check Editor's Review

Top Pick for Speed &Reliability

Recognized for its lightning-fast performance,WeSuggest highlights our tool as a go-to solution for exporting OST files without needing Outlook installed.

Learn More

Trusted by the CNET Community

With a solid 4-star rating on Download.com,we are proud to be a community-favorite for reliable and accurate mailbox migration.

Read User Ratings

Awarded for Best User Experience

Customer happiness is our biggest win. This award reflects our commitment to making complex data migration simple and stress-free for everyone.

View Award Details

Get Your Mailbox Back in 4 Simple Steps

How OST to PST conversion works—add file,scan,preview,convert. No Outlook required.

  1. Add OST File

    Open the tool and load your OST data using single file,multi-file,or folder mode. This step prepares mailbox data for safe scanning and conversion.

    Add OST file – step 1 screenshot
  2. Scan and Analyze Mailbox

    The software scans emails,contacts,calendars,and attachments to build a complete recovery-ready mailbox structure without modifying source data.

    Scan and analyze mailbox – step 2 screenshot
  3. Preview Emails and Folders

    Review mailbox folders and message content before export so users can verify exactly what will be converted.

    Preview emails and folders – step 3 screenshot
  4. Convert and Save

    Choose output format such as PST,MBOX,EML,or Office 365 migration,apply filters,and click Convert to save mailbox data in the required format.

    Convert and save – step 4 screenshot

Supported Export Formats

For more,email migration and backup are used for migrating OST to PST,MBOX,EML and more.

MBOX Export

You can easily convert Outlook OST files into the MBOX file format,which enables access to inaccessible Outlook data in MBOX-supported email clients like Mozilla Thunderbird,Apple Mail,Eudora,and Mutt.

TGZ Export

This tool helps you export all Outlook mailbox items from OST into Zimbra TGZ format. Exported data works with all Zimbra versions and ensures seamless,efficient migration from OST to Zimbra.

EML Export

Extracting all emails from Outlook OST files and saving them in EML format is simple with this advanced tool. It supports creating EML files for clients like Thunderbird,Windows Mail,Apple Mail,eM Client,Outlook Express,and Maildir.

EMLX Export

Converting OST files to EMLX is effortless with this conversion tool. It extracts all or selected folders from OST data and creates EMLX files for supported clients like macOS Mail and Apple Mail.

MSG Export

Move Outlook OST emails into MSG format while preserving metadata and message properties. You can use exported files with compatible applications such as Microsoft Outlook,Microsoft Exchange,and Mailbird.

HTML Export

If you want to access emails without an email client,HTML is a practical option. Select specific folders or emails and open exported HTML files in web browsers like Chrome,Firefox,Safari,and Edge.

MHTML Export

Quick OST to MHTML conversion helps access Outlook data with MHTML-supported platforms including Microsoft Outlook,Microsoft Exchange,and Mozilla Thunderbird (with add-ons).

PDF Export

This advanced OST conversion option helps create PDF documents from emails and allows separate attachment saving. It simplifies access,sharing,and long-term archiving in a universally readable format.

VCF Export

Convert OST contacts into VCF format for broad compatibility across devices and applications,including iPhone,Android,Outlook,Thunderbird,and contact management systems.

CSV Export

If you need contacts in spreadsheet-friendly format,this option creates CSV files from Outlook OST contacts. It simplifies import into Excel,spreadsheet applications,and other email clients.

IMAP Migration

Import Outlook emails into online email accounts through IMAP. This option helps transfer offline OST emails to IMAP-supported services such as Gmail,Yahoo,and Office 365.

NSF Export

Lotus Notes is a powerful email platform,and this tool helps move all Outlook data into Lotus Notes NSF files. You can create both mail.nsfand name.nsfwith ease.

Why Softaken is the Preferred Choice Over Competitors?

A quick performance and feature comparison to help you decide faster.

FeaturesSoftakenOther Brands (Generic)
Conversion Speed✅ Fast❌ Slow
Attachment Handling✅ Embedded attachment support❌ Partial or inconsistent
Large File Support✅ 150GB+ tested❌ Often unstable on large files
Customer Support✅ 24/7❌ Email only / delayed

This comparison focuses on practical migration performance and enterprise readiness.

Proven in Real-World Scenarios

📌 Real Use Case

Our support team recently helped a client recover a 170GB orphaned OST file that other tools couldn’t open. This software handled it in under 3 hours—full folder structure and attachments intact.

🔬 Internal Testing

Our team tested this with a 150GB corrupted OST file and it completed conversion in approximately 90 minutes with full folder hierarchy and attachments intact. No Outlook or Exchange connection required.

🏢 About Softaken

Since 2015,Softaken has been delivering email migration and recovery solutions. Trusted for secure mailbox recovery and compliance backup by IT professionals worldwide.

Is This OST Converter Tool Safe?

Non-destructive scanning

Most people worry about the original file getting corrupted during recovery or conversion. We remove that worry by opening your OST in read-onlymode. The tool builds what is essentially a mirror of your data in a new PST—without rewriting or modifying the source file on disk. Your original OST stays exactly as it was.

Zero cloud interaction

Mailbox data is sensitive—we know that—so our design keeps it local. Privacy isn’t a bolt-on;it’s how the product is built. Unlike browser-based converters,the whole job runs on your PC:nothing is uploaded to our servers,shared,or passed through third-party APIs. Your machine is the only environment that ever handles the file.

Forensic-level accuracy

When you migrate or archive,the message body alone isn’t enough. We map the details that matter—To,CC,BCC,and precise timestamps—into the new PST. Folder hierarchy is carried over carefully so the export still feels like your original mailbox,not a flattened dump of messages.

Choose the Best Plan for Your Conversion Needs.

Compare feature limits and full access before you choose.

FeaturesFree DemoFull Licensed Version
Item Export25 items/folderUnlimited
Batch ConversionLimitedFull batch support
License Validity1-monthLifetime
UpdatesNoFree for 1 year

Before vs After Conversion

❌ OST inaccessible,server down,errors
✅ Clean PST with emails,contacts &attachments

Trusted by Leading Clients

Organizations and enterprise teams worldwide rely on Softaken solutions.

Trusted by IT Professionals Worldwide

Three featured customer quotes below (5★ each). Average and total count match the live visitor rating at the top of this page.

★★★★★

"Recovered all emails from a corrupted OST. Very easy to use."

John K.
John K.IT Admin • USA
★★★★★

"Batch conversion saved hours when we migrated our department. Handles huge mailboxes without a hitch."

Sarah M.
Sarah M.System Engineer • UK
★★★★★

"Recovered mailbox after Exchange crash. Support was very responsive."

David L.
David L.MSP • Australia

Frequently Asked Questions About Outlook Data Migration (Updated 2026)

Tested and Recommended by IT Administrators for Enterprise-level Mailbox Migration. Quick answers below on safety,data loss and conversion.

Softaken OST to PST Converterruns entirely on the OST file:no Outlook profile,no Exchange session,no MAPI connection. Four stages:load,deep scan,preview,export.

  1. Load your OST— Browse to a single Outlook .ost(ANSI or Unicode,including compressed or encrypted where our engine can unlock it) or add several files for batch migration. We stress-test 150GB+archives in the field. There is no hard-coded size capin the converter.
  2. Deep scan &structure recovery— Our recovery pass reads the offline store and reconstructs the folder treewhen the OST is orphaned or the header is damaged—typical after an Exchange move,domain change,or crash where Outlook will not mount the file.
  3. Preview in the viewer— Drill into folders and open items before export:HTMLand plain textmail views,Internet headers,attachment lists,plus contacts and calendar detail—so you commit to disk only after you have eyeballs on the data.
  4. Export &PST controls— Choose PST,MBOX,EML,MSG,PDF,or Office 365,then Convert Now. For PST,use date-range filters,optionally strip attachments,and split output PSTs(e.g. 2GB/5GB chunks) when you are handing archives to legacy Outlook that hates single multi-terabyte files.

Full cutover,legal-hold subsets,or one-off recovery—all follow that same workflow. For Outlook-native workarounds and admin context,see our how to convert OST guide.

OST to PST conversion is the process of converting Outlook OST files to PST format for convenient backup and access.

It contains emails,contacts,calendars,attachments and other mailbox data.

You require the conversion of OST to PST for the purpose of data recovery,migration,and backup.

You get your mail back after a crash,corruption or a big upgrade—without fighting the server.

Yes—we focus on badly corrupted OST filesand heavy recovery scenarios.

Recovery mode plus deep scan pull out as much as we can from a bad file. For troubleshooting,see fix OST corruption /open OST without Outlook.

No,there is no restriction on the size of the file when converting from OST to PST.

Large OST files may be converted without any limitations.

Yes—folders and subfolders stay in order while you convert.

All emails,folders and subfolders remain unaltered.

Batch conversion is available in the Business and Enterprise modifications.

Simultaneously processing multiple files is feasible.

This version is for Windows. For Mac,we have a separate version that only converts OST to PST;you can try by clicking here.

You can export to PST,MBOX,EML,MSG,PDF,HTML and more—pick what fits your workflow.

No,you don’t need Outlook installed. We know how frustrating it is when the Exchange server is down and you can’t access Outlook—that’s why our tool works completely standalone.

OST files are used to store offline Exchange data,whereas PST files are portable Outlook data files.

PST files are simpler to backup and transmit. For further information,consult our guide on the differences between OST and PST.

Yes. The software is completely secure and data-safe;it operates on a copy of your file and does not alter the original OST.

Our featured customer quotes on this page are all 5★;money-back guarantee;used by IT professionals and enterprises worldwide.

Emails,attachments,contacts and calendars are exported without loss of data integrity during the conversion process.

Even from corrupted or deserted OST files,the advanced recovery mode extracts the maximum amount of data.

Yes. IT teams stick with us for a 99.9% recovery success rate when migrations go sideways—plus day-to-day recovery,backup and archival.

Backed by 24/7 support and a money-back guarantee.

Still have questions? Contact our 24/7 support or try the free trial today!