Christian Kreibich Chris Kanich Kirill Levchenko Brandon Enright Geoffrey M. Voelker Vern Paxson Stefan Savage On the Spam Campaign Trail. 2008 LEET http://www.usenix.org/events/leet08/tech/full_papers/kreibich/kreibich.pdf conf/nsdi/2008leet db/conf/nsdi/leet2008.html#KreibichKLEVPS08