Outlook Offline Storage Table (OST) files are used by Microsoft Outlook to store a copy of your Email mailbox data on your local machine. However, there are situations where you might need to convert an OST file to a Personal Storage Table (PST) format, which is more portable and can be easily backed up or transferred. In this blog post, we will explore how to convert OST to PST in C#.

Why Convert OST to PST?

There are several reasons why you might need to convert an OST file to PST format:

Data Portability: PST files can be easily moved across different systems and devices, making them ideal for data migration or backup.

Access without Exchange Server: OST files are tied to the Exchange server and cannot be accessed directly if the server is unavailable. Converting to PST allows you to access your data offline.

Recovery of Data: In case of corruption or accidental deletion of mailbox items, converting OST to PST can help recover and restore the data.

Archiving: PST files are often used for archiving old emails and mailbox data, ensuring that the main mailbox remains uncluttered.

OST to PST Converter - C# API Installation

You need to ensure that Visual Studio IDE and .NET framework is installed in your environment as a prerequisite for the conversion. Subsequently, configure Conholdate.Total for .NET with the NuGet installation command below:

PM> NuGet\Install-Package Conholdate.Total

Convert OST to PST in C#

You can convert an OST file to PST format in C# by following the steps below:

  • Load the source OST file using the PersonalStorage class.
  • Convert OST to PST format with the SaveAs method.

The sample code below shows how to convert OST to PST in C#:

Free Evaluation License

You may get a free temporary license to avoid the evaluation limitations and test the APIs to their full capacity.


The OST to PST conversion process ensures that your data is easily portable and can be accessed across different systems and applications. By following the steps outlined in this blog post, you can efficiently convert your OST files to PST in C#. However, if you need to discuss any of your requirements or queries, please feel free to reach out to us at forum.


What is the difference between OST and PST files?

OST (Offline Storage Table) files are used to store a local copy of mailbox data from an Exchange server, allowing offline access. PST (Personal Storage Table) files are used for storing emails, contacts, and calendar items, and can be used independently of the Exchange server.

Can I convert an OST file to PST without Outlook?

Yes, you do not need to install Outlook to convert an OST file to PST format from within your C# application.

How secure is this OST to PST conversion process?

This conversion process is secure, as it runs locally on your machine, ensuring your data remains private and protected.

What types of data can be converted from OST to PST?

This conversion approach supports all types of mailbox data, including emails, contacts, calendars, tasks, and notes from OST to PST.

See Also