Mozilla Thunderbird, the Mozilla SeaMonkey project is a community effort to "deliver production-quality releases of code" based on the former Mozilla Application Suite.
As a result, Mozilla Seamonkey is the new-generaton Web browser suite that combines the Firefox Web browser, Thunderbird e-mail client, and Composer HTML editor. Much of the core code in Seamonkey 1.0 is shared with the Firefox 1.5 browser, but from the outside, it represents the look and feel of early Netscape/Mozilla releases.