To backup your Office 365 data, I would suggest you use the Office 365 backup tool (datarepaittools). By using this advanced tool, you can easily backup your Office 365 data and restore your mailbox from an Office 365 backup. This tool supports Windows 10, 8.1, 8, 7, Vista, and Windows Server 2008 and 2003. It has multi-format saving options for mailbox data like PST, RTF, MSG, EML, HTML, and PDF. You can try a free demo version of this tool to learn more about its features.