Because Debian mailing lists accept messages from non-subscribers, and
our spam filters have not yet achieved sentience, our mailing lists
are not 100% spam free.

But you can help us get better!

http://www.debian.org/MailingLists/ 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, but
there's always room for you to help us improve them.