Hello Ano It’s not matter that solution is payable or free for migration of precious Outlook PST to Mozilla Thunderbird. You need to move your important data from Outlook to Thunderbird without any risk. I know a simple method that helps you to complete your task securely.
Firstly convert your Outlook emails to EML and contacts to VCF formats with powerful PST extractor program. After achieving conversion of PST to EML you can import single or multiple EML files into thunderbird without using any additional tool.
You can use App to Convert PST to EML - http://www.pcvita.com/pst-xtractor.html
Free & Secure Process to Import EML Files into Thunderbird!
• Go to your thunderbird email account and create a new sub-folder as desired name
• Select all EML files (ctr+a) from folder where converted EML are stores
• Drag all them and drop into new created sub- folder at once.
• All EML files are imported successfully you can open them with thunderbird.
Look Free Import Process- http://www.pcvita.com/faqs/import-eml-into-thunderbird.html