This is an important book - well worth your time, and, more importantly, accessible to non-specialists (such as BDMs):
<http://www.amazon.com/Spam-Nation-Organized-Cybercrime--Epidemic-ebook/dp/B00L5QGBL0/>
<http://www.amazon.com/Spam-Nation-Organized-Cybercrime--Epidemic/dp/1402295618/>
It's not about spam, per se. It's about the global underground economy, and includes a lot of insight into internecine warfare amongst online criminals, including DDoS attacks with huge collateral damage footprints; and also talks about the origins of the Blue Security fiasco and subsequent DDoS, DDoS attacks against Spamhaus, etc.