It's hard to conceive of what could be in Trump team email that would be more damaging than some of the things that Trump said that were known before the election. Such as:
"I could stand in the middle of 5th Avenue and shoot somebody and I wouldn't lose voters"
and
"Grab ’em by the pussy. You can do anything."
And that's just the tip of the iceberg. It seems like Trump said something outrageous every other day.
If Trump's email had him directing his underlings to cooperate with the Russians to hack the DNC, then maybe that would have hurt. But maybe that wouldn't have been sufficient. Maybe there would have needed to be a video attachment with Trump saying exactly that? Not just words?
Seriously. Outside of evidence of Trump specifically directing people to cooperate with Russia to commit felonies, what email could have been sufficiently damaging to Trump?