Yes, his system probably would kill spam. It would also kill a whole
lot of other things, including most of the reasons I use email.
Absent further evidence, I say "kook".
I don't think he's so much "kook" as simply an engineer who has spent
so much time engineering that he's lost touch with the world of
humans. It's an affliction which many of us with a propensity toward
geekdom have experienced to some degree, but we all have different
times at which course correction kicks in. If one does not stop to
regroup and reevaluate how one's outward life compares to one's inner
truth, one can end up much like Mark.