Sylpheed 3.1 Beta 6
Sylpheed is a simple, lightweight but featureful, and easy-to-use e-mail client (mailer, MUA).
Sylpheed uses GTK+ GUI toolkit. The newest version of Sylpheed works with GTK+ 2.4 or later (2.6 or later is recommended).
Sylpheed is a free software distributed under the GNU GPL (the library part is GNU LGPL). You can freely use, modify and redistribute it under the license.
Simple, beautiful, and well-polished user interface