Rated 5 out of 5 stars

Xubuntu 13.10. Thunderbird 24.2.0. ImportExportTools 2.8.0.4. Locale UTF-8.Cannot export messages with subject in Russian - only "____" in filenames.
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When I go in Tools --> ImportExportTools --> Preferences, click on "Filename" tab and uncheck the first checkbox ("Use just alphanumeric characters in export") - I see sctrange file name "C Днем Рождения!-20140202-0202-266687.txt".
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But when I go in Tools --> ImportExportTools --> Preferences, click on "Filename" tab and change "Codepage for filename symbols" from UTF-8 to win1251 - all became OK :)

This review is for a previous version of the add-on (2.8.0.4). 

Go in Tools --> ImportExportTools --> Preferences, click on "Filename" tab and uncheck the first checkbox ("Use just alphanumeric characters in export"), it should fix this.