Use Outlook PST File Converter tool, which can help you to mass import PST into Office 365 file format with attachments. This tool manages the folder hierarchy which allows user to save their converted PST files into Office 365 into same folder structure according to their choice. It has very simple user friendly graphical interface, users can easily handle and work with software without needed any technical knowledge. There is no file size limitation; you can convert number of files at a time without any problem. This software supports all the Windows editions like 11, 10, 8.1, 8, 7, etc. editions. You can also use the free demo version of the software without any cost.