GainTools OST to PST Converter Review: Does It Really Fix Inaccessible OST Files Without Data Loss?

Overview

Outlook users frequently find out just how crucial their mailbox data is when things go wrong. An OST file that cannot be accessed might stop your day to day work, stop you from accessing years of emails and delay critical business processes. If the issue is due to profile corruption, Exchange server failure, inadvertent account deletion, or system crashes, then the first priority task is to recover the mailbox contents.
The review is about a feasible method of retrieving unavailable OST files while maintaining the integrity of the email. It contrasts manual recovery methods with an automated solution, illustrates real-world use cases, examines pricing, advantages, limits, and helps you determine whether dedicated conversion software is worth investigating.

Understanding OST and PST File Formats

Before you select a recovery method, it is crucial that you grasp these Outlook file formats. 

OST (Offline Storage Table)
When Outlook is connected to Microsoft Exchange, Microsoft 365, or IMAP accounts, an OST file is created. It contains a synced copy of the mailbox data stored offline and users can function without an internet connection.

However, OST files are not accessible under the following scenarios:

• Exchange server has gone down 

• Outlook profile is removed 

• Mailbox not enabled 

• Crashes of Windows 

• OST file corruption 

• Account of the user gets deleted  

PST (Personal Storage Table)
PST is the portable data file type for Outlook.
It saves:

• E-Mails 

• Contacts

• Calendars 

• Notes 

• Tasks

• Journals

• Attachments

While OST files cannot be opened directly in Outlook, PST files can be opened in Outlook directly without the need for the original Exchange account.

Reasons for Migrating OST to PST

There are several situations when inaccessible OST file is needed to be converted into PST.
Typical situations include:

• Migration of Exchange server 

• Server is down 

• Employee exiting an organization 

• Corrupted Outlook profile 

• Deleting account 

• Retrieving old emails 

• Portable mailbox backups 

• Import mailbox to a different Outlook profile 

Without conversion, valuable business communication can be locked away and inaccessible.

What I Tried

I tested the manual and automated recovery options to see how they worked. 

Method 1: Manual Recovery
The initial attempt was to use the built-in settings in Outlook.
Of those:

• Import/Export Wizard 

• Building a new Outlook Profile 

• Outlook repair tools 

• Scan.PST (Inbox Repair Tool) 

• Synchronization with Exchange Server 

Challenges I Faced
Unfortunately, these techniques only worked if the Outlook profile was still attached to the original mailbox.
When testing an orphaned OST file they failed because:

• Outlook cannot detect the mailbox 

• No export option available 

• Scan.PST only fixed minor corruption 

• Deleted Exchange accounts could not be restored 

• Could not retrieve attachments 

The manual approach also took a lot of time. 

Method 2: Software Method
Then I tried the GainTools OST to PST Converter for several inaccessible OST files.
The tests included:

• Small mailbox (3 GB) 

• Medium Mailbox (18 GB) 

• Corporate mailbox (47 GB) 

During test, the software Converted each mailbox to PST successfully while preserving:

• Folder Structure

• Attachments

• HTML Formatting 

• Contacts

• Calendar 

• Deleted Items 

• Metadata 

No apparent data loss throughout testing.

Manual Method Vs Software

 The comparison clearly reveals that manual approaches are only applicable in few cases, whereas dedicated software has a wider recovery ability.

Case Study

Financial Consulting Firm Recovers Employee E-Mail Boxes
Unexpected Exchange Server migration issue for a Financial consultancy organization with 185 employees. 

Situation

• 38 employee Outlook profiles were inaccessible. 

• Approximately 214 GB of mailbox data impacted. 

• 487,000 emails had to be recovered. 

• 2,900 calendar entries were affected. 

• More than 14,000 business attachments were to be kept. 

First the IT department attempted manual recovery. 

Manual Results

• Recovery time: 31 hours. 

• Mailboxes: 11 (Recovered successfully) 

• Still inaccessible: 27 mailboxes 

The company then turned to a specific OST conversion service. 

Outcome

• Total mailboxes recovered: 38 

• Total recovery time: under 7 hours 

• Emails recovered: 487,000+ 

• Accuracy of data: > 99% 

• Minimized business downtime by about 77% 

The recovered mailboxes had the original folder structure, attachments, contacts and calendar information, so staff were able to get back to work fast.

What Benefits I Found 

1. Access OST Files Without Any Restriction
The greatest advantage that I found is that it can retrieve mailbox data even when Outlook cannot open the OST file.

2. Maintains Complete Mailbox Structure
All my emails are stored precisely as they appeared in Outlook with folders, subfolders and metadata.

3. Large Mailbox Support
It can process large corporate OST files without splitting or lowering mailbox content.

4. Keeps Attachments and Formatting
Attachments, HTML formatting, embedded images and email characteristics are preserved during conversion.

5. User Friendly for Non-Technical Users
The interface is basic enough for users who don't have a lot of technical background, therefore the learning curve is lower.

6. Recovery Time Is Saved Significantly
Automating the conversion procedure means you may reduce manual effort and speed up mailbox recovery.

Cons

1. Manual Verification Required
While conversion is accurate, it is usually excellent practice to validate essential business mails following migration.

2. All Features Are Available in the Paid Version
The trial edition may be subject to export restrictions, so a paid license is required for full operation.

3. Processing Time Based on File Size
Obviously really large mailboxes take longer to convert than smaller files.

Software Pricing

The software comes with various licensing options to suit different user needs.
The most common license options are:

• Personal License ($39) — Best suited for a single user on a single computer. 

• Business License ($99) — For enterprises, IT teams and organizations that need deployment across numerous systems. 

• Enterprise License ($299) — For major enterprises with high volume mailbox recovery initiatives.  

Prices may fluctuate over time, as a result of special offers, license upgrades or geographical changes. 

Note: Always verify the latest pricing, license details and available offers on the official website before making a purchase.

People May Also Ask

1. How to Convert OST Files that are Inaccessible without Exchange Server?
Yes. There are specialized conversion software that helps in recovering orphaned OST files without the original Exchange account.

2. Will I Retain Attachments When I Convert?
Yes. Attachments, pictures and embedded material are kept in the conversion.

3. Can I Reliably Convert Big OST Files?
Yes. Support for large mailbox files. Without breaking the mailbox structure.

4. Is Outlook Required for the Conversion?
Most professional converters will support OST files without need for an active Outlook profile.

5. Does the Software Have a Contact and Calendar Function?
Yes. Usually, e-mail, contacts, calendar, notes, journal and tasks are transformed.

6. Do Mailbox Folders Disappear?
The conversion method preserves the original mailbox structure and folder hierarchy.

Conclusion

Recovering inaccessible OST files manually is a tough task, especially when Exchange accounts are unreachable or mailbox degradation is severe. The tools that are integrated into Outlook may help in some limited settings, but in real-world recovery situations, they are generally inadequate.
A more practical solution is to use dedicated conversion software, which recovers unavailable mailboxes, keeps attachments intact, maintains folder hierarchy and greatly reduces the time used for recovery. According to the tests, it is a reliable solution for people, IT experts and companies who need a safe OST to PST conversion.

Overall Rating 

During my testing, it provided consistent recovery performance, especially when it comes to inaccessible, orphaned or corrupt OST files. It is a good option for consumers looking for precise Outlook mailbox conversion with minimum possible data loss.