You can convert OST file to PST file format. You can try this software Convert OST File to PST. This software Support all Outlook version including 2003, 2007, 2010, 2013 and 2016. The free trial version which transfers the first 10 items from OST file. The application securely exports emails, contacts, calendar entries, notes, tasks, and much more into PST format. on Windows OS. For more information: mailsclick.com/convert-ost-file/