What Is the best way to import your OST file into a Gmail Account? I would suggest you SysInspire OST to PST Converter tool. It can convert your OST file into PST and also 15+ other formats including PST, Office 365, EML, EMLX, HTML, MSG, CSV, VCF, Yahoo Mail, IMAP Account, Gmail, Zimbra Desktop and many more. This software interface is easy to understand. Anyone can use this software if he is from nontechnical background.