The best way to save OST mailbox data for offline viewing anywhere is the
PCinfotool OST to PST Converter. It is an advanced and effective tool that can easily save OST mailbox data and Outlook OST files to multiple formats like EML, MSG, and MBOX without any data loss, and you can view them offline anywhere, anytime without any trouble. It provides a trial version, which helps users understand if they can use this without getting the full version.