A friend asked me the other day, what exactly is bulletproof hosting? Laura Atkins has complained before, on this very blog, that Google is a bulletproof hosting provider. Google doesn't exactly fit the criteria, but Laura's frustration was legitimate; stemming from Google's seeming unwillingness to follow up on certain types of spam complaints. So what is the accurate definition of a "bulletproof hosting" provider?
A "bulletproof hosting" provider is typically defined as a company that knowingly providers web hosting (or other services) to spammers, intending to ignore spam complaints and take no action against the spammer's use of their services.
Brian Krebs (Krebs on Security) explains in more detail on his blog. See: Body Armor for Bad Web Sites.