I used the following procedures to install Thunderbird 3.0 with the Enigmail add-on to send encrypted email. I found myself needing to do this when I upgraded Thunderbird via yum from the CentOS repository. Instead of going back to the older version, I decided move ahead since I had also had trouble with the 64 bit version of Thunderbird when using the Enigmail add-on. Also, I liked the changes made from Thunderbird 2.0 to 3.0 that I saw in Fedora. Note: I found that I needed to remove the old Enigmail add-on before upgrading. Then after following the steps below, I installed the latest Enigmail add-on.

# yum –disablerepo=rpmforge install cvs zip gcc-c++ glib2-devel gtk2-devel fontconfig-devel libnotify-devel libIDL-devel alsa-lib-devel libXt-devel freetype-devel pkgconfig dbus-glib-devel curl-devel autoconf213 xorg-x11-proto-devel libX11-devel libXau-devel libXext-devel

The following was installed from the rpmforge repository.
# yum install mercurial
# cd /usr/local/src
# wget ftp://ftp.mozilla.org/pub/mozilla.org/thunderbird/releases/3.0/source/thunderbird-3.0.source.tar.bz2

# tar -xjvf thunderbird-3.0rc2.source.tar.bz2
# cd comm-1.9.1/
# vi .mozconfig
…
ac_add_options –prefix=/usr/local/thunderbird
ac_add_options –disable-tests
ac_add_options –disable-debug
ac_add_options –enable-crypto
ac_add_options –enable-optimize
ac_add_options –enable-static
ac_add_options –enable-static-mail
ac_add_options –enable-application=mail
mk_add_options MOZ_CO_PROJECT=mail
…
# make -f client.mk configure
# make -C mozilla tier_base
# make -C mozilla tier_nspr
# make -C mozilla tier_js
# make export
# make -C mozilla/modules/libreg
# make -C mozilla/xpcom/string
# make -C mozilla/xpcom
# make -C mozilla/xpcom/obsolete
# cd mailnews/extensions/
# wget http://www.mozilla-enigmail.org/download/source/enigmail-1.0.0.tar.gz
# tar -zxvf enigmail-1.0.0.tar.gz
# cd enigmail/
# ./makemake -r
# make
# cd /usr/local/src/comm-1.9.1
# make -f client.mk build
# gmake install