You can use the SysInspire OST to PST Converter utility to open or import things from an offline Outlook Data File (. Ost). This utility converts an OST file to a PST file without making any internal modifications (such as date, subject, or attachments). Show a live preview of the process. It's an antivirus and internet scanner that you can trust completely. It works with all Windows operating systems, including XP, 7, 8, 10, and later. If you're still not sure, you can download a free demo file that converts OST 25 items to PST files.
Read More:- Convert OST File to PST