There are many users who wants to move Outlook database into MBOX based email client like: Entourage, Thunderbird, AppleMail, Spicebird, Pocomail, Eudora, Netscape, Mulberry, SeaMonkey, OperaMail, ClawsMail, Evolution, Mozilla Mail. In this Situation you can try this PST to MBOX Converter Software that will help you to Export Outlook PST file to MBOX file. This Software Support 20+ Email Clients.
Note: You can also use the free demo version of this software. Where you can also save 30 emails per folder at free of cost.