I would like to recommend Good working third-party tool name of KDETools OST to PST converter tool for converting from OST file to PST file. You don’t need any technical knowledge for executing this. GUI of this ost to pst conversion tool is user-friendly and informal to use. You can even download the free version of this tool. Through This OST to PST full version software you can convert OST file to PST file and also save OST file to PST, EML, EMLX, MSG, HTML, MBOX, vCard, VCF, Zimbra, Live Exchange server, OLM, NSF, Office 365, and etc.
1- Export OST file in 15+ file formats.
2- Split large PST file after converting.
3- Filters Messages By Date/Size.