Step by Step Guide to use Stellar Converter for OST

OST is an Outlook data file created by Outlook when you set up or configure Exchange server account and enable the Offline mode (Cached Exchange Mode). The OST file stores mailbox items, such as emails, contacts, attachments, notes, journals, etc. It allows user to access their Outlook emails and do certain changes, even when the system is offline.

The changes are later synchronized with the mailbox on the server as soon as the system connects to the internet. This provides a seamless and lag-free user experience. Also, the OST file is encrypted with MAPIEntry GUID key and hence, requires authorization from the MAPI profile to access the emails and other data.

Thus, an OST file and its content cannot be opened, accessed, or imported into any other Outlook profile. Furthermore, if your MAPI profile is deleted or disabled from the Exchange server, you cannot access your emails stored in the OST file as authorization fails. Such OST files are referred to as orphaned OSTs.

Other issues, such as synchronization failure or errors caused by Exchange database dismount or server failure, could lead to a permanently inaccessible OST file as Outlook fails to reconnect to the Exchange server.

In such cases, a third-party OST to PST converter software, such as Stellar Converter for OST, comes in handy. The software converts encrypted, inaccessible, and orphaned OST files of any size to PST with 100% integrity and precision.

It can also export the mailbox items, such as emails, attachments, contacts, notes, tasks, journals, etc., from an OST file directly to a live Exchange Server mailbox or Office 365. So let us have a quick look at the software, its features, and how you can use it to recover your emails from OST files.

Stellar Converter for OST- An Overview

Stellar Converter for OST is a powerful OST to PST converter software to convert, backup, and migrate mailbox items from large, inaccessible, encrypted, or orphaned Outlook OST files to another Outlook profile on Windows or Mac.

The software extracts and converts all mailbox items, such as emails, attachments, contacts, messages, journals, notes, etc., from OST file to Outlook importable PST format. The folder hierarchy and structure remain intact after conversion. It also recovers lost or accidentally deleted emails from the OST file during conversion.

In addition to PST, you can also convert and export the mail items from OST files to EML, MSG, PDF, RTF, and HTML formats. It supports MS Outlook 2019, 2016, 2013, 2010, 2007, and Office 365. It can convert OST files created by any Outlook version.

The software is available in two editions:

1.Stellar Converter for OST – Corporate Edition

The Corporate version allows you to convert and save or export up to 5 mailboxes to PST. It previews unlimited mailbox items and provides other saving options, such as PST, MSG, EML, RTF, HTML, and PDF.

2.Stellar Converter for OST – Technician Edition

In addition to all the features available in the Corporate edition, the Technician edition offers some advanced OST conversion options, such as:

 Batch conversion to convert multiple OST files to corresponding PSTs simultaneously
 Compacts and splits large PSTs based on date, size, or email address to safeguard resultant PST from corruption caused by oversize
 Exports OST directly to Office 365 and live Exchange
 Exports OST mailbox data to an existing Outlook profile
 Exports all contacts in CSV file format

Both editions are available as Demo versions that you can download to evaluate the software performance. The demo version allows you to scan and preview OST mailbox items for free. You can also convert and export up to 20 items per folder to PST format. To save all OST mailbox items, you must activate the software using a valid activation key.

How to Use Stellar Converter for OST?

Stellar Converter for OST is an easy-to-use software with intuitive GUI. Any user can convert the OST to PST file format in a few clicks. However, it does require MS Outlook installed on the system that meets the following minimum system requirements:

 Processor: Intel-compatible x86 or x64 Processor
 Operating System: Windows 10, 8.1, 8, or 7 OS
 Memory: 4 GB RAM (8 GB Recommended)
 Storage: 250 MB storage space on HDD or SSD

The steps to convert OST by using the software are as follows:

1.Install and launch Stellar Converter for OST and click ‘Browse’ to choose the OST file. You may also use the ‘Find’ button to locate the OST file if the location is unknown.
Outlook repair

2.Click ‘Convert’ to start the scan and extract the mail items from the OST file.
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3.The software displays an enhanced preview in a three-pane window, including deleted mail items in ‘Red.’
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4.Select the mail items and email folders from the left pane you want to convert and then click on ‘Save Converted File.
5.From the ‘Save as’ dialog box, choose the desired format, such as PST. Then click ‘Browse’ and select a save location.
Outlook repair

In Technician Edition, you have more saving options, such as MBOX, DBX, Export to Live Exchange Server, Office 365, or existing Outlook profiles. Further, you can choose to save PST normally or compact or split/filter and save the PST file.

Outlook repair

6.Click ‘OK’ to save the OST mailbox items to PST. Similarly, you can choose MSG, EML, RTF, HTML, PDF, DBX, or MBOX format and select a destination to save individual or multiple emails.

To export OST to Office 365 or live Exchange, you need to enter the user credentials, such as user ID and password.

To save OST mail items to an existing profile, select ‘Export to Existing Outlook Profile’ and choose an existing profile from the option.


Compared to various OST to PST converter software available in the market, Stellar Converter for OST stands out due to its intuitive user interface, ease-of-use, and performance.

To learn more about the performance of Stellar Converter for OST, check out this OST benchmark study report. The study was done in collaboration with Lisa Hendrickson – a solutions consultant and industry expert for Microsoft Outlook, Office 365, and Exchange.

It provides a more insightful view of various OST to PST converter software performance on parameters, such as speed, consistency, precision, and completeness.

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Step by Step Guide to use Stellar Converter for OST was last updated June 9th, 2021 by Kelly Singh

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