This email was obviously written with Bayesian filters in mind. It's seeded with around 150 random, long words of the kind that you'd not expect to find in a spam, but that are varied enough that it's quite likely that at least _some_ of them will be in your filter as high indicators of non-spamness. →
Copyright does not prohibit reverse-engineering, except (thanks to the DMCA) where the thing being reverse-engineered is a copy-prevention mechanism. This is because copyright law is all about the making and distributing of copies. Under regular property law, once you have bought something, you're perfectly within your rights to take it apart and see how it works. →