They don't have to read his email, just analyze it algorithmicly. They already generate some kind of index of how many times each interesting word is used, oth

They don't have to read his email, just analyze it algorithmicly. They already generate some kind of index of how many times each interesting word is used, otherwise they couldn't provide ads or fast searching. They only have to view that index as a histogram to reveal all kinds of interesting stuff about Fred's business -- information that he gets an advantage from keeping private.