I have verified that this package works for ppc64. Please add the ~ppc64 KEYWORDS to mail-client/mailx-8.1.2.20021129-r2. my USE Flag is "gtk2 altivec ppc64 -gnome cjk jpeg gif png tiff truetype".
add deps on bug #55668 liblockfile and bug #55669 mailx-support
Thanks Yuta
stick a fork in it