In some language environments, legacy encoding (character set) is
preferred for e-mail messages: For example iso-2022-jp in Japanese
charset.conf defines mapping between language context and legacy character
set for service messages sent by Sympa. If you want to enable legacy character
set support, simply copy sample charset.conf onto configuration
# cp /usr/local/share/sympa/defaults/charset.conf /usr/local/etc/sympa/charset.conf
And set the legacy_character_support_feature parameter value in
/usr/local/etc/sympa/sympa.conf to on.