Classified material has a header which says top-secret, secret, confidential. Nothing, and I will repeat this and this is verified in the report by the Department of Justice, none of the emails sent or received by me had such a header.
Presidential candidate
the NBC Commander-In-Chief Forum 
Subjects: candidates-biography,corrections-and-updatesSpeaker: hillary-clintonSpeaker Job Title: Presidential candidateParty affiliation: democrat