An important part of a better experience through themes is choosing the correct fonts.
bug 465633 is looking into shipping a better font with Thunderbird
The Deja Vu font is freely available under a license that is likely compatible with the Mozilla license. It supports a large number of glyphs, likely making it our default font choice for every platform it's installed in.
Most platforms have a specific set of fonts included by default. Thunderbird should take advantage of the best and most available platform fonts by choosing them in order.
- Deja Vu
- Bitstream Vera