if you want secure migration then you have to use MBOX to Outlook Converter. This is the best GUI based application so it easy to use it and allows you to transfer multiple MBOX to PST format. it supports 30 email clients MBOX data such as Apple Mail, Thunderbird, Entourage, Netscape, SeaMonkey, Sparrow Mail, The Bat, Claws Mail etc. The tool is 100% secure and reliable to migrate MBOX to PST and other given formats.