ost to pst conversion is a matter of dealing and export between two types of Microsoft Outlook, which means this software is your best option how to convert ost to pst. You can easily export inbox off-line folder file (.ost) to personal folder file (.pst) in Microsoft Outlook by selecting the File ► Open ► Import ► Export to file ► Outlook data file.
If you do not have access to Outlook, you have to rely on other 3rd party conversion or recovery tools that help users with transferring Outlook data. These are often quite expensive.Open OST file Open PST file
An e-mail management tool distributed with Microsoft Office suite
Mac version of the popular e-mail client and personal information manager from Microsoft