procmailとの組み合わせ
.forward
"|IFS=' ' && exec /usr/bin/procmail -f- || exit 75 #~/Maildir/"
.procmailrc
PATH=/bin:/usr/bin:/usr/local/bin MAILDIR=$HOME/Maildir DEFAULT=$MAILDIR/ LOGFILE=$MAILDIR/procmail.log LOCKFILE=$HOME/.lockmail :0 *^Subject.*\[mx\].* |conv.rb :0 *^(To|Cc|Bcc).*n9d.* .aaa/