Claws Mail is an email client (and news reader), based on GTK+ featuring:

 * Quick response
 * Graceful, and sophisticated interface
 * Easy configuration, intuitive operation
 * Abundant features
 * Extensibility

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.

This requires libetpan.  If you want to be able to print html emails, you
will also need to have html2ps installed.