Guidelines on Electronic Mail
Security-FEDGOV
http://csrc.nist.gov/publications/nistpubs/800-45-version2/SP800-45v2.pdf
Its deeper than that. Official govt emails are required to be on govt owned systems or govt approved systems. Anything remotely sensitive has tighter controls.
Certainly she had classified information which cannot be on those types of systems.
This should put her in jail but she won’t even have to answer for it.