What is the easiest way to move emails from a PST file to MBOX format?

I have some old Outlook PST files that I want to use with an email client that supports the MBOX format. I’m looking for a reliable PST to MBOX Converter that can handle emails and their attachments without making the process complicated. Ideally, the tool should preserve the original folder structure and email details during conversion. Has anyone used a PST conversion tool for this purpose and can share their experience or recommended approach?