How can I convert Thunderbird to Outlook on Mac OS? Simply download and use the latest Thunderbird to Outlook Converter for Mac program, it helps you to convert your Thunderbird to Outlook format by keeping complete data safe and secure such as; Emails, Contacts and Calendars details. Software works perfectly fine it support batch file conversion from Thunderbird to Outlook format with no data loss at all. Download the free Thunderbird Converter for Mac tool to test its working efficiency now.