http://downloads.sourceforge.net/sylpheed-claws/claws-mail-extra-plugins-3.7.9.tar.bz2

cd rssyl* &&
./configure --prefix=/usr &&
make

make install

http://pgp-tools.alioth.debian.org/

caff_snapshot2009.03.17.tar.bz2

Needed patch: caff-mailto-cmd.pl2.diff
My patch is based on this one: http://www.fabiankeil.de/sourcecode/caff-mailto-cmd.diff

svn export svn://svn.debian.org/pgp-tools/trunk/caff &&
cd caff &&
patch -p1 -i ../caff-mailto-cmd.pl2.diff

Create a configuration file for caff:

cat > ${HOME}/.caffrc << "EOF"
$CONFIG{'owner'} = 'Steffen Pankratz';
$CONFIG{'email'} = 'kratz00@gmx.de';
$CONFIG{'mailto-cmd'} = "claws-mail --compose 'mailto:%a?subject=%S&bcc=%b&body=%B'";
$CONFIG{'keyserver'} = 'subkeys.pgp.net';
$CONFIG{'keyid'} = [ qw{AA6205D0B08823DB} ];
EOF

Run caff (each line of the keyfile consists of the key id or the fingerprint):

./caff "`cat keyfile`"