At the risk of sounding like a neophyte, why don’t they just ask the people who communicated with Lois Lerner to step forward (or risk action if they don’t) and give them the other side of the mail? We know many of the folks that need to be asked, just let it be known that in a scan, if you have mail from LL, you better step up.
Because the other side of that mail are names like Barack Obama and Valerie Jarrett --