Convert the Outlook OST file to Gmail using the SysInspire OST to PST converter software. It has a very simple and user-friendly UI. This tool is simple to use for everyone. You may also convert Outlook OST files to EML, HTML, Yahoo, Gmail, Office 365, MSG, ICS, Zimbra, MBOX, and EMLX, among other formats. This application also includes email filtering and live preview, which are two of the most useful features. Get 25 mailbox items from each folder with the free demo version of this tool.