Damascus is a GTK+ 2.x client for the Gale communication protocol. It is somewhat modelled after IM/ICQ-style interfaces. If you don't know what Gale is, this client probably won't be very useful; you need a valid Gale key to send anything, and Damascus can't generate them (yet). Gale is also scary and confusing.
kmMail is a PHP-based mail program, based on the mail functionality of Keftamail and is being developed by current Kefta employees. It is meant to be a framework for putting a web-based mail program on your site, but is still robust enough to drop into your current site with little to no modification. The goals of kmMail are MIME compliance, speed, low overhead, and an enjoyable user interface.