Linux Online - Networking / Email Clone of the excellent NeXTSTEP Mail.app, Licence: GPL. Very powerful GUI e-mail tool. JMR, Version: 0.7.25

WebMaster Resource Sites: Email Application & Tool Sites: A comprehensive collection of hundreds of freeware and shareware webmaster tools selected for their usefulness to novice and professional webmasters.

Web 2.0 applications: Google vs. Yahoo vs. Microsoft. Yahoo, Microsoft, and Google all connect their e-mail apps to their own IM, calendars, and other tools to keep you from clicking elsewhere.