Thunderbird to Outlook Express convert mail messages from Thunderbird files (mbox format) to separate .eml messages and store them in folders as you see folders in Thunderbird. Conversion is done for all Thunderbird folders and if the folder is empty then an empty folder for Outlook Express is created too.
Import to Outlook Express you make in that way find one folder created by Tbird2OE, go into and select all messages here, using mouse drag & drop these messages into Outlook Express folder. Select messages in another folder and go to point. Languages Czech, English, Slovak.