If you're dealing with a large set of Outlook MSG files and need to convert them to EML format for Thunderbird, I highly recommend checking out the
BetaVare Export MSG to EML software. I recently used it while helping a colleague transition a bunch of MSG emails into Thunderbird, and it worked flawlessly. The tool lets you import entire folders, choose EML as the output format, and handles the conversion quickly while preserving everything—attachments, formatting, and important fields like To, CC, and Subject. It even maintains your folder structure, which is super helpful for keeping things organized. The interface is clean and beginner-friendly, so no technical skills are needed. Plus, it works great on Windows, and supports all Outlook versions without needing Outlook installed. If you want a dependable, no-fuss solution for bulk MSG to EML conversion, this one’s definitely worth trying.