The easiest and most effective way to open or import an MBOX file into Outlook is to use a trusted tool like ToolsGround MBOX to PST Converter. This tool converts MBOX files to PST format, which is supported by Outlook. The process is simple: first, add the MBOX file to the tool, then convert the file to PST format. Next, easily import the converted file using the “Open & Export” option in Outlook. This method not only saves time but also ensures data security.