Sylpheed is one of the best GTK-based e-mail clients for the Linux platform – it just doesn’t look it. The author is considering to make the program theme-able, but this feature has not been implemented yet. However, by simply replacing the original Sylpheed artwork and the derived header files, a customized binary can be compiled.

The complete Sylpheed source code can be downloaded here

DOWNLOAD

Icon theme for Sylpheed 2.x : Sylpheed2.0_icon-set.tar.gz
Icon theme for Sylpheed 3.x : Sylpheed3.0_icon-set.tar.gz