Tenfourbird is unofficial build of Mozilla Thunderbird for PowerPC based Mac OS X.
Tenfourbird uses changesets of TenFourFox.
Latest version is 38.9.0.
This is really last v17 release. Next stable release is scheduled on v24.2.
Version 17.0.11.1 is PowerPC G3 only release.
You can check integrity of files by SHA1 hashes. It also signed by OpenPGP key of t_mrc-ct[at]users.sourceforge.jp. The public key could get from here or OpenPGP Keysever.
All Langpacks are not updated since 17.0.4