the only tool I am aware of that I know works is http://www.maildev.com/buy/#mt it is not free. I have no connection with the company other than they provided a copy to test.

mardigee said

I have successfully downloaded Thunderbird, but I need to import my e-mail contacts and my side folders (with messages) from IncrediMail. How can I do this?

I haven't tried the program yet, but it looks like exactly what I need.  Thank you, Matt.