Claws Mail is an email client (and news reader), based on GTK+, featuring
Graceful, and sophisticated interface
Easy configuration, intuitive operation
Robustness and stability
The appearance and interface are designed to be familiar to new users coming from other popular email clients, as well as experienced users. Almost all commands are accessible with the keyboard.
The messages are managed in the standard MH format, which features fast access and data security. You'll be able to import your emails from almost any other email client, and export them just as easily.
Lots of extra functionality, like an RSS aggregator, calendar, or laptop LED handling, are provided by extra plugins.
Claws Mail is distributed under the GPL.