To convert OST files into PST, EML MSG, MBOX, and HTML file formats use MailsDaddy OST to PST Converter Tool. In addition, If you want to convert the OST file’s contact and calendar folder, then you can save it in .csv/.vcf and .ics file format respectively. The software has many other important features like- repair OST file damages, maintaining read & unread status of e-mails, merging PST files, showing a preview, and many more.

Vist here: Convert OST to PST