One of the best, in my opinion, comes highly recommended. Software very fast converts PST File to Thunderbird and it's called eSoftTools PST to MBOX Converter Software convert PST File to Thunderbird converter device. It has a quick output with simple steps. The device can convert PST File to Thunderbird forward with all mailbox items such as - emails, contacts, calendars, attachments, tasks, notes and others. For the entire order, There is a free trial version available.