OST to PST Converter

Yes. The existing OST file can be processed directly without connecting to an Exchange Server. This is useful when the original account is unavailable, a mailbox is disconnected, or recovery is required after an Exchange Server failure. The recovered mailbox data can then be saved as a standalone PST file.

Yes. An orphaned OST file can be processed even when the original Exchange or Microsoft 365 account is no longer available. The file can be opened directly and its supported mailbox data extracted without restoring the original mail profile or Active Directory connection.

Yes, in many cases. The software can recover readable mailbox data from a corrupted Outlook data file, depending on the extent of the damage. Severely damaged files may contain unreadable or incomplete items.

Yes. Multiple Outlook data files can be processed in a single batch, eliminating the need to handle each file individually. Command-line and PowerShell workflows can also be used for scheduled or unattended processing.

Yes. Email attachments are preserved with their corresponding messages and stored in the resulting PST file.

Yes. Large Outlook data files can be processed without splitting the mailbox into multiple PST files. Alternatively, it can create a separate PST file for each Outlook folder, giving you more control over how the converted data is organized.

Microsoft Outlook is not required to open or process the source file. The software can read it directly without connecting to the original Exchange Server or Microsoft 365 account.

The size of the resulting PST file does not necessarily match the size of the source OST file. Differences are normal and can occur for several reasons.

Reasons for a smaller PST file:

• OST files may contain deleted or outdated versions of items that are no longer needed. During conversion, only the current supported Outlook data is exported, so this unused data is not included in the PST file.
• OST and PST files use different internal storage structures, so the same Outlook data can occupy different amounts of disk space.

Reasons for a larger PST file:

• Make sure you are exporting to a new PST file rather than adding data to an existing one. Use the Overwrite mode option to control this behavior.
• The internal storage structure of the PST file and the Outlook version used to create it can affect its size.
• When exporting a large number of emails, Outlook may use additional space while creating and updating the PST file.

First, make sure you are converting to a new PST file rather than an existing one. You can control this using the Overwrite mode option in the OST 2 PST.

Classic Outlook has a default size limit of 20 GB or 50 GB for PST and OST files, depending on the Outlook version and configuration. If the resulting PST reaches this limit, you can increase the Outlook data file size limit or export the OST data into multiple smaller PST files.

The System.OutOfMemoryException error indicates that the system does not have enough available memory to complete the conversion. This can occur when processing a large OST file or a large amount of Outlook data.

If you are using 32-bit Microsoft Office, consider switching to 64-bit versions of all components required for the conversion. To process very large OST files more efficiently, we recommend using:

• Microsoft Windows (64-bit)
• Classic Microsoft Outlook (64-bit)
• OST 2 PST (64-bit)

Using 64-bit components removes the memory limitations of 32-bit applications and allows the converter to process significantly larger OST files.

The free demo version allows you to evaluate the OST 2 PST before purchasing a license. Export is limited to 15 items per folder. To remove this restriction and export all data from an OST file to PST, purchase a valid license and activate the software to the full version.