>>todsac+(OP)
The real punchline is that this is a perfect example of "just enough knowledge to be dangerous." Whoever processed these emails knew enough to know emails aren't plain text, but not enough to know that quoted-printable decoding isn't something you hand-roll with find-and-replace. It's the same class of bug as manually parsing HTML with regex, it works right up until it doesn't, and then you get congressional evidence full of mystery equals signs.