[savedbygrace]

That seems to say it was for the the IRS Office of Chief Counsel:

http://www.irs.gov/uac/Office-of-Chief-Counsel-At-a-Glance

Not the entire IRS.

[PJ-Comix]

Fox News was just now talking about SonaSoft. Even if the email archives are limited to office of Counsel, then those might be revelatory.