Do you have the best software to import OST files into Outlook.com? I would suggest you the SysInspire OST to PST converter tool. This is the best software to convert an OST file into PST file and 15+ others formats like PST, Office 365, EML, EMLX, HTML, MSG, CSV, VCF, Yahoo Mail, IMAP Account, Gmail, Zimbra Desktop and many more. This software also provides you the best features like email filtration and mass conversion. It can also provide you free version in which you can convert 25 items in each folder.