How about a subpoena for all email accounts of everyone Lerner sent an email to, and all those accounts holders that sent an email to Lerner.
There are two copies of every email, one in the originators account, and one in the recipients account. Subpoena the non-Lerner account copies of the emails in question.
If I were Lois Lerner, I would stay far away from Fort Marcy ppark.
That's the problem. We don't know for sure who she sent email to outside of the IRS (although we suspect).