Here are the general steps to convert OST files to PST format:

Method 1: Professional OST to PST Converter.
Select a Converter: You may choose any one of the reliable OST to PST converter software like Stella Converter for OST .
Download and Install: Download the software you have chosen and install it on your system.
Launch the Application: Now open the application, and select the OST file that you want to convert.
Scan the OST File: It scans the OST file to extract all emails and other items.
Preview Data: It previews the extracted emails, contacts, and other items after scanning.
Select PST File: Export option along with the choice of PST format, then give a location to save the new PST file.
Convert: It will initiate the process of conversion. When the process gets completed, it gives you the PST file for your OST data.
Method 2: Manual Export from Outlook
If you still have access to the Outlook profile to which the OST file is linked, you can manually export the data:

Open Outlook: Open Outlook and make sure you are logged into the profile that is linked with the OST file.
Go to File: Click on “File” in the top left corner.
Select Open & Export: Choose “Open & Export” from the menu.
Import/Export: Click on “Import/Export” to open the wizard.
Choose Export Option: Check “Export to a file” and click “Next.
Select PST Format: Check “Outlook Data File (.pst)” and click “Next.
Select Data to Export: Check the folders you want to export (e.g., Inbox, Sent Items) and click “Next.
Choose Save Location: Specify where to save the PST file and complete the wizard.

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