I agree w/Biz Insider - A big tech law firm that is almost certainly working on contingency rather than billing $500/hr is a fair indication that there's some meat to this case.
Even if they lose, think about it, DLA probably already have some spin about how they are just being "professional" about due diligence and doing the best they could for their client. No loss in reputation.
Plus, the legal costs of pursuing a case like this is likely to be extremely high. If the evidence is so weak to be thrown out even before it comes to court, then I don't think they would pursue it.
It would certainly be possible to fool someone that such emails were legit depending on what sort of verification job they did.
If not, where are they from?
Have they been subjected to forensic investigation?
Has the source been substantiated?
Was the due diligence done on these emails, specifically?
I'm a cynic about such things though :)