This is Enigmail for PowerPC Mac OS X. (Unofficial build)
System Requirements
Mac OS X 10.4 or later (PowerPC)
Thunderbird or compatible application (i.e. Tenfourbird) version 31 or later
Files
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.