Suppose you had 30,000 purloined emails, and access to the resources of a major state. A simple disinformation move would be to have minions read them all, and select and modify a tiny number (say, 5 or 10) to become explosive (add a racial slur, a phrase about keeping ill gotten gains, etc.). Make those changes, and then release the whole mess*. Wait for the press to find your land mines, enjoy. Yes, these changes could probably be disproved in court, but that's not the goal of a disinformation campaign.
In this scenario, the press will inevitably become collateral damage, but the perpetrators are not likely to care (and may even view that as a side-benefit).
* If there are integrity checks, such as MD5 sums, either hack them or remove them. I don't think that will hinder anyone with an intelligence agency behind them.