I'd be careful about using the term "bulletproof" in this context. Before reading the article, I assumed it was talking about sending spam without getting blacklisted.
Read the article's disclaimer:) I think even if you'll have all possible things setup super-correctly and you'll put word `viagra` into the Subject field - nothing will help you.
Would be interesting to get a perspective from whoever manages email for Pfizer corporate. How many spam filters out there must they have to battle against to get their legitimate email about Viagara through?