Install free Charamel and Silvermel Themes for Thunderbird

Charamel is a free skin for Thunderbird featuring a “Creamy Sugary Experience”.

Charamel is offered as bundle – it installs “Silvermel and Charamel XT” extension to support font uppercase and letter spacing for labels on Firefox’s sidebars, Thunderbird’s folder pane, Thunderbird’s Address Book and Thunderbird’s Account Configuration window.

You may also like to check how to customize almost everything in the interface of Thunderbird