I know that you have posted before that you find reading a spouse's e-mail and/or eavesdropping on their phone calls to be gross, offensive, evil, etc. And, I know that if someone suggests that it is not nearly as uncommon as you seem to think it is, you accuse them of condoning the behavior. But, I'll take that risk.
I challenge you to find any research/data that suggests that snooping on spouses' phone calls and/or e-mails is a "gateway crime" to murder. As I've posted several times before, typically lawyers tell clients that are going through ugly separations/divorces to expect that this is going to happen. That doesn't make it right, but it happens. A lot. However, I until someone points us to actual data that draws a correlation between this behavior and murder, I don't believe it. There are tons of spouse's going through divorces who snoop and don't commit murder and there are tons of spouses who commit murder, but didn't snoop on e-mail.
This was a mistake on NC's attorney's part. If she had experience in family law, knew that Brad was technical, and knew that there was already suspicion of him eavesdropping on phone calls, it was foolish of her to be sending info that she didn't want BC to see via e-mail.