Outlook: How to Convert OST to PST

In this guide, you will learn about Outlook OST and PST files, why you might need to convert OST files to a PST, and how to convert OST files to PST format.

What is an OST file?

An OST file, or Offline Storage Table file, is a data file that is created by Microsoft Outlook when you add, or sign in using, an IMAP, Exchange, Outlook.com, or Microsoft 365 account. OST files allow users to work offline and synchronize offline changes to the mailbox server once the Internet connection is restored. They contain a user’s mail items, such as emails, contacts, and calendar events, etc.

OST files are by default encrypted using MAPIEntryID, making it difficult to open or import them into another Outlook profile or account. Therefore, you must convert the OST file to a PST (Personal Storage Table) file to access the OST file mail items in another account or profile.

Below are some key points to remember about OST files:

• OST files store a local synchronized copy of all the mailbox data on the mailbox server.
• They enable Outlook users to have offline access to their emails, calendar items, contacts, and more.
• The file is commonly used in corporate or business environments where Microsoft Exchange (on-premises) or Microsoft 365 accounts are used.
• OST files improve Outlook performance as mail items are stored locally in the file and changes are synchronized to the mail server periodically.
• OST files cannot be accessed, opened, or imported into any application or Outlook account/profile on same or other PC.

What is a PST File?

Personal Storage Table (PST) files are another common Outlook data file format used to store messages, calendar events, and other mail items. However, unlike OST files, Outlook users can easily import or open PST files in any Outlook client.

Here are some key points about PST files:

• PST files are created by Microsoft Outlook when a POP3 (Post Office Protocol) email account is added.
• Outlook downloads the mail items from the server to the local PST file.
• PST files are used for backups, archiving mail items, and transferring  mailbox data from one system or Outlook client/profile to another.
• Unlike OST files, PSTs are quite portable. You can easily import PST files into any Outlook profile or account and get access to the email items.

Reasons to convert OST files to PST

Outlook users may need to convert an OST file to PST file format in the following situations:

1. OST file becomes orphaned or inaccessible

OST files become orphaned or inaccessible when the Outlook profile or account is deleted from the mail server or the Exchange/Microsoft 365 mail server is no longer available.

2. Prevent data loss

Sometimes, you need to extract mail items from an OST file but can’t access them since the file is either too large for Outlook to process or has inconsistencies that could lead to damage or corruption.

3. Transfer or move/migrate mail items to another Outlook instance/profile

You need to convert the OST file to a PST when you want to move or transfer emails from one system to another or when backing up mailbox data before re-configuring or reinstalling Outlook, or reinstalling the operating system.

4. Manage OST file size

When the OST becomes too large for Outlook to handle, you can reduce the size of the mailbox (OST) by offloading the mail items to a local PST.

Methods to convert OST to PST

There are several methods for converting OST files to PST format. Based on your scenario/situation, you can follow the methods discussed below.

Method 1: Convert OST to PST using Outlook Import Export Wizard

You can easily convert OST to PST files by using the Import/Export wizard in Outlook. For a successful conversion, ensure:

• You have access to the original Outlook profile that is linked to the server.
• You have admin access to the system.

The steps to convert the mail items from OST files to PST format are:

• Open Outlook. From the menu, select File > Open & Export andclick Import/Export.

• On the Import Export wizard, select Export to a file and then click Next.

• Then, click Outlook Data File (.pst) and Next.

• Select the OST file from which you want to extract and export mailbox items or data.
• Make sure to tick the Include subfolders checkbox and then click Next.
• Click Browse to specify or select the location to save the PST file.

• Click Finish to start converting the OST file items to PST.

Limitations of this method

A few limitations of this method are:

• Users can convert OST to PST files only if they have access to their original Outlook profile connected to the mailbox server.
• If the OST file is inconsistent or the profile is unavailable, there is no option to convert the OST to a PST.

Tips to convert OST to PST successfully and safely

Here are some tips you can follow for converting OST to PST files in a safe and secure way:

• Always create a backup of the OST file before the OST to PST conversion begins. This is essential for avoiding data loss in case of an error.
• Always check and update Outlook, Windows, and any third-party add-ins. This helps avoid compatibility issues.
• The disk where you save the converted OST file should have enough free storage space.
• Check that you have the necessary permissions to edit the OST file and that the OST file is not accessed, opened, or in use by another application, such as antivirus/security programs.

Method 2: Use third-party OST to PST converter software

There are various third-party tools available to convert OST files to PST format. These tools simplify the OST to PST conversion process. While evaluating third-party OST to PST converter tools, consider the following factors:

• User-friendly interface

The tool you are planning to use should have an intuitive interface that makes it easy to convert the OST files to PST format.

• Complete data integrity and precision

The OST to PST converter software must maintain the integrity and consistency of the converted data.

• Conversion speed and efficiency

Select a OST to PST converter tool from a reputable developer or organization that’s known for its fast and efficient conversion. This is quite important when you need to convert large or multiple OST files to PST format.

• Compatibility with Outlook and Windows versions

Before purchasing the OST to PST converter tool, verify that the tool supports the Outlook and Windows OS versions you are currently using.

One such tool that meets all the above factors is Stellar Converter for OST. The tool can scan and convert large inaccessible and orphaned OST files to PST format with complete integrity and precision. It supports OST files as large as 50 GB or even above. Additionally:

1. It allows you to search individual messages within the OST and save them to PST and other formats. Furthermore, it offers the option to filter the messages by subject, date, etc.
2. It lets you convert all the OST file items, including emails, notes, attachments, calendars, and more to PST file format.
3. It also exports the data directly to Microsoft 365 or live Exchange Server account.
4. It can save OST file items in other file formats, such as PDF, RTF, HTML, MSG, and EML.

Let’s see how to use this tool to convert OST files to PST format:

• Download and install Stellar Converter for OST from the official website.
• Launch the software and click the Choose Mailbox Manually option to browse and select the OST file you want to convert.

• Click Convert. The software will start scanning the OST file and show a preview of all the mail items.

• Select the mail items you want to save to PST file and click Save Converted File.
• Choose PST format and click Next.

• Select a location where you want to save the PST file and click OK.

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What to do Next?

Once you have successfully converted the OST file to PST format, you can:

• Scan the PST file using SCANPST to ensure there are no integrity issues or inconsistencies in the PST file.
• Open Outlook and go to File > Open & Export > Open Outlook Data File to open and access the PST file.
• Look for missing emails or any other discrepancies in PST file.

Efficiently convert single or multiple OST files to PST format

You may need to convert OST files to PST format when you want to transfer mailbox data to other Outlook profiles or if the file becomes orphaned or inaccessible. By following the methods outlined in this guide, you can efficiently convert single or multiple OST files to PST format.

You can use an advanced third-party OST to PST converter tool, such as Stellar Converter for OST, when you don’t have access to Outlook or the profile associated or linked with the OST file is deleted or not available. The tool makes it easier for anyone to extract the mail items from inaccessible or orphaned OST files and save them to PST format with complete integrity and precision.

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FAQ

• Can I convert OST to PST without Outlook?
  Yes, you can convert OST files to PST without Outlook using a third-party OST to PST converter tool, such as Stellar Converter for OST. This tool can open large, encrypted, inaccessible, or orphaned OST files and convert them to PST format with complete integrity in a few clicks.
• How long does the conversion process take?
  The time required to convert an OST file to PST depends on the size of OST file, the hardware configuration and available resources on the system, and the disk read/write speed. It typically ranges from a few minutes (for small OST files) to several hours (for large OST files).
• What should I do if the conversion fails?
  If the OST conversion fails, you can check for Outlook and Windows updates and install them, scan the OST file using SCANPST or the Inbox Repair tool, make sure that you have sufficient permissions to access the OST file, and have enough storage space to save the new PST file.
• Can I convert multiple OST files at once?
  Yes, many third-party OST to PST converter tools, including Stellar Converter for OST, support batch OST to PST conversion. This helps users convert multiple OST files simultaneously, and saves time and effort.