You can also take the help of Mailsware Thunderbird Converter Toolkit. The software provides you the 100% safe and secure conversion. It allows to bulk convert Thunderbird emails to PST along with attachments. The software does not require the installation of any external application.
Please visit the link to know more: http://www.mailsware.com/thunderbird-converter.html
RE: How to Convert Thunderbird Emails to Outlook PST Format