"Lessons learned" from Wikileaks publishing all of Hilary and the Democratic National Committee's emails is that email is dangerous. Don't use it anymore. One of my neighbors here in west Austin is the guy who sold the Russian Federation all their email servers and devices in the early 1990s when he worked for Dell. You know what they've done with all that equipment? They trashed it. Russian government employees have been forbidden from using email now for years.
It's looking more likely that Wikileaks received the DNC and Hilary emails from the NSA through a proxy. NSA monitored Hilary's server as soon as she set it up, and they saw all the "pay for play" bribery schemes she ran while Secretary of State. It's people in NSA who are bringing down Hilary and the Democrats, not the Russians.
NSA like most intl agencies does not volunteer to send over evidence of crimes to law enforcement. In fact even when law enforcement asks NSA for help they usually don't cooperate. There is a firewall between the intl world and that of LE. And for the people at NSA seeing what Hilary was doing they knew even if they reported it that Obama and Holder and now Lynch would do nothing but cover it up.
So the answer to the question is this. Bleachbit will hide data from LE and your spouses' investigator and lawyer. But it won't work against the NSA.
The NSA has on file every email sent by everyone everywhere in the world. It's hard to believe but they actually have accomplished that. It's not metadata mining. They actually have all the emails sent by everyone everywhere.
The Russians have the right idea.