Yes. You need to set the font for each and every encoding that you encounter. Western and Unicode should indeed cover the vast majority of cases for those of us using English or a European language that uses a similar (roman) alphabet. When a message turns up that looks odd, look at its headers, identify the encoding being used and check the formatting set-up for that encoding. (Personally I use a grep like utility to globally change all font settings in the relevant preferences file.) My experience is that this works, but I've been following a discussion elsewhere where another user seems to be saying, like you, that these settings don't seem to work, and I wonder if we have a new bug. Does anything change if you run Thunderbird in its Safe Mode?