I can't get Thunderbird 13.0.1 to use proper font sizes for message text.

I have configured all font settings to use Ubuntu Mono 16, and set minimum font size to 16. Nevertheless, I get two different font sizes for message bodies depending on the encoding specified in the Content-Type header, both of them wrong.

When the encoding is omitted, or when it is set to iso-8859-1 or us-ascii the message is displayed using a font that seems to be of size 12 or 13. This font size is also used when composing new messages. When increasing the configured font size, the displayed text increases size and seems to stay about 3 or 4 units below the one I set.

When the encoding is set to utf-8, the message is displayed using a very tiny font, size 8 or 9. This is close to unreadable. The font size used for such messages are constant, and does not change when I modify the configuration for fonts or minimum font size.

I had similar problems with earlier versions of Thunderbird, but it has gotten a lot worse after the last update, with the font size for utf-8 messages refusing to increase above the unreadable.

Is there any way to circumvent this annoying problem?


After some searching on the net, I found the solution to my own problem. I include a description of it below to hopefully save others with the same problem some effort:

At the top of the dialog window under Edit > Preferences > Display > Formatting > Fonts > Advanced, there is a drop-down menu labelled Fonts for. This is initially set to Western, meaning all settings below only applies to messages with those encodings. To change fonts for messages with utf-8 and other non-western encodings, choose Other Languages in the drop-down menu then set the font types and sizes to the same as you have for Western.

  • Apparently the idea of classifying utf-8 as a non-western encoding was introduced in version 13 of Thunderbird. I find this rather illogical, living in the western part of the world where we've been using utf-8 as standard for many years now. – Lars Haugseth Jun 27 '12 at 10:34

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