10 CFR 95.41: External receipt and dispatch records.

Each licensee, certificate holder or other person possessing classified information shall maintain a record that reflects:

(a) The date of the material;

(b) The date of receipt or dispatch;

(c) The classification;

(d) An unclassified description of the material; and

(e) The identity of the sender from which the material was received or recipient to which the material was dispatched. receipt and dispatch records must be retained for 2 years.