Are you kooking for the best OST to MBOX Converter then I would suggest you to use ZOOK OST to MBOX Converter tool. It is dedicated tool to convert OST data files to MBOX format with attachment, that enable users to access or migrate OST files into MBOX supported email clients like Mozilla Thunderbird, Apple Mail, Opera Mail, Netscape, Opera Mail and many more. It is most useful tool when it comes to export OST files to MBOX format.