For all we know, it's just Flynn's transition emails with others, of which Flynn gave permission for the FBI investigators to read his email correspondences as part of Flynn's cooperation in exchange for his plea deal....
pretty sure if it were that simple it would have been verified as such by now.
my problem is if he got them illegally then we need to follow that process and if that disallows evidence, so be it. follow the law, not the desire.
anti-trump people won't care how anything is gotten if it will take him down. that is a very dangerous ground to be on but again, they just don't care.
I agree that it should be done legally and there is no doubt that Mueller did it LEGALLY, however they were acquired...he is an upstanding law enforcement man and knows the letter of the law upside down and inside out.... and he has no intention of messing up this case with a technicality.
so Trump can whine all he wants about it being unfair.... and all that jazz....
it means nothing if the investigators followed the law (which I'm certain they did)....if they did not, (which is highly unlikely) then they can't use the info to prosecute.