export emails from PST file in Outlook 2010 to Thunderbird
Solution 1:
The only tool that actually reconstructs headers is OutlookFreeware.com's Export Messages to EML Format utility. It's free and easy to use. I recommend it because I'm one of its developers.
Solution 2:
The mozillaZine article Import .pst files treats the problem.
You need to have both Thunderbird and Outlook installed on the same computer,
while Outlook is defined as the default email client, and then use Tools -> Import -> Mail
within Thunderbird.
As you have already seen the above article, please let us know why it doesn't work for you.
You could also try the Thunderbird PST Import plugin.