In Mozilla Thunderbird, you can choose the font used for reading mail quite freely — and you can pick your favorite color, too.
Change the Default Font Face and Color for Incoming Mail in Mozilla Thunderbird
To change the font used by default for reading mail in Mozilla Thunderbird:
- Select Tools | Options... (or Thunderbird | Preferences... on a Mac) from the menu.
- Go to the Display category.
- Click Text Color: and Background Color: under Colors to change the font and background colors.
- Click Fonts....
- Choose the desired font face and size under Serif:, Sans-serif: and Monospace:.
- Mozilla Thunderbird uses the font type specified under Proportional: by default. Make sure this is Sans Serif to use the Sans-serif: font, for example.
- To override fonts specified in rich-text messages, make sure Allow messages to use other fonts is not checked.
- Using your default fonts instead of those specified by the sender may distort some messages' visual appeal.
- Click OK.
- Close the preferences window.
Apart from choosing a different font and font size, you can also zoom in on messages while reading comfortably.