If you need a smart yet reliable solution, so you can try the advanced third-party software, KDETools for OST to PST import tool. The software quickly & deeply scans .ost files to fix Outlook .ost files errors, corruption issues. And its application has a good process to convert OST to PST Outlook included you can save data many file formats such as- Zimbra, Gmail, MBOX, office 365, Live Exchange server, EML, EMLX, vCard, ICS, and etc.
• No condition to install MS Outlook to convert OST to PST.
• Well facility of Batch Conversion option to add file/folder.
• Export bulk OST into PST Outlook includes many file formats.
• Transfer email Meta Properties To, Subject, Bcc, Cc, From, Date and etc. into Outlook without changing the email meta properties.
• Supports each windows OS version.
More info- 100% free ost to pst converter