We are aware that Debian-Mailinglists aren't 100% spam-free, but if
you can't accept that, don't subscribe to our lists.

http://www.debian.org/MailingLists/ also contains some hints how you
can help us to improve the ham/Spam-ratio, you can also simply bounce
(As in mutt) spams you get through our lists to:
report-listspam@lists.debian.org

Our filters currently stop about 50000 incoming mails per day, 2500 make it
through to the filters, i think this is a good job.