cover letter and cc list

What does it take to send the cover letter to all people which are listed in the Cc: list of the following patches? Each patch has a different Cc: list. The "git send-email --help" command suggests that this cmdline should do it. But the cover letter goes just to the address listed in --to=:

env TMPDIR=/dev/shm LC_ALL=C git send-email -M --stat --annotate \
        --cover-letter --cc-cover --to=$address \
        $base..$head

Thanks,

Olaf