If you are looking for the best method for converting OST files to PST, I recommend
MacSonik OST to PST Converter. It helps users to easily convert the OST files to PST files and many other file formats, as well as to multiple email clients. It converts OST files to MBOX, MSG, EML, PDF, EMLX, CSV, GIF, JPG, TIFF, HTML, etc. Additionally, the software offers a Batch Conversion feature that allows users to easily convert multiple OST files to PST format at once, without any data loss. Apart from this, the software is compatible with all versions of the Mac and Windows operating systems.