I tried to install thunderbird 2.0.0.0 with USE=replytolist. This tried to pull inx11-plugins/replytolist-0.2.0, which ultimately failed, as it only has amd64 and ppc keywords. Please add x86 keyword. I copied the ebuild to my local overlay, added the ~x86 keyword, and was able to build the plugin and thunderbird.
~x86 + ~ia64 done. Arches, please keyword x11-plugins/replytolist-0.2.0 for mail-client/mozilla-thunderbird-2.0.0.0. Thanks.
~sparc'd.
added ~ppc64
~x86-fbsd added.