Sam, a cleared DoD employee, receives an e-mail message on his NIPRNET account that contains classified information. Who should he notify first of this incident?

The security manager

Explanation:

Classified information is any document, data, or material that is recognized by an institution of government as being  or containing sensitive, delicate, important information has to be guarded. The law and particular regulations restricts access to classified information to those with the required  level of security clearance and those who have stated need to know as such that wrong conduct or mismanagement of classified information is punishable under the law.

can you explain it better

using the bering strait was the best transportation system.