(EDIT) Ok, i just copied the Windows Thunderbird Profile Folder into the one in Mac OS. First i just copied the wrong one, so problem is solved...

How can i import my Windows Thunderbird Mail Account to Mac OS X?

Hello again, i found the following interesting workarounds how to share the thunderbird mail directory over windows and linux, which is even more interesting: Here are all interesting links inside. Or specific here and here. It`s Linux related stuff and i will see how to make this work in Mac OS.

Or use the ImportExportTool (mbox), a plugin for TB

I share my Thunderbird data between Vista and OS X. It's pretty much the same process between Linux and Windows, but since I don't trust OS X abilities to handle NFS (I usually cannot access certain directories), I've copied all the data to a third partition - FAT32 formatted - and told everyone the profile was there (Absolute path) editing profile.ini on both OSs.