Mozilla Thunderbird is a redesign of the Mozilla mail component. The goal is to produce a cross platform stand alone mail application using the XUL user interface language. The intended customer is someone who uses Mozilla Firefox (or another stand alone browser) as their primary browser and wants a mail client based on mozilla that “plays nice” with the browser. Mozilla Thunderbird has the following other editions available: Mozilla Thunderbird for Linux and Mozilla Thunderbird for Mac OS X.

Download: Mozilla Thunderbird v1.5 (Freeware)
View: Release Notes
Homepage: Mozilla