The best third-party tool is eSoftTools OST to PST Converter, which has many different features including a batch conversion option that will let you convert a huge number of OST folders or just convert the password-protected Outlook OST file. it can also convert OST files to various formats such as Gmail, MBOX, EML, EMLX, CSV, Yahoo, PST, Office365, Zimbra, and vCard. Users can download the Demo version of the software from eSoftTools' official websites for more information and convert the selected 25 items in the OST file into various formats.
Read More:- Export OST to PST files