TenFourBird is a modern ThunderBird email client for PPC G3 through G5 Macintosh with Mac OS X 10.4 or 10.5 systems!
Unofficial Mozilla Thunderbird build for PowerPC Mac OS X (based on TenFourFox. )
Unofficial Mozilla Thunderbird build for PowerPC Mac OS X based on TenFourFox.
Latest version is 17.0.2.
You can download file releases of Tenfourbird project from List of release files
System Requirements
Operating System: MacOSX 10.4 Tiger
http://en.sourceforge.jp/projects/tenfourbird/