Thunderbird

Thunderbird is a free, open source, cross platform email, RSS and chat client developed by the Mozilla foundation. Thunderbird is an email, newsgroup, news feed, and chat (XMPP, IRC, and Twitter) client. It runs on variety of platforms and the source code is available and can be compiled on any architecture. Some of the features are message management, junk filtering, extensions and themes, standard support. It supports almost all platforms. Thunderbird can manage multiple e-mail accounts at the same time.