Unless they update the ToS, the only ban-hammer worthy offenses are spamming, messing with their networks or them getting a court order to take down the account due to illegal activity.

And, Assuming they're not lying, they can't see what's in your e-mail to see if you've been saying naughty things.

Is it perfect? Probably not. If a deranged mob comes after them I can't 100% guarantee they won't fold. But, short of setting up your own e-mail server with its own encryption and DDOS protection you're not really going to get better.