If you need a way to convert MSG emails with attachments to Thunderbird, then After conducting numerous user reviews, I have determined that the ToolsBaer MSG to MBOX Conversion Tool is one of the best solutions to convert MSG emails with attachments to Thunderbird MBOX file format. You should use an automated method to load MSG extensions into MBOX without losing data. This professional approach eliminates the need for a supported email application at work. This is the best option if you want to work without installing Thunderbird. This works with all Outlook file versions and connects to Thunderbird, Mac Mail, and Entourage. Install on Windows. This tool works well with Windows 11, 10, 8.1, 8, 7, XP, and Vista operating systems.