Security Labels in Internet Email
K. Zeilenga, A. Melnikov · 2015
This document describes a header field, SIO-Label, for use in Internet email to convey the sensitivity of the message.This header field may carry a textual representation (a display marking) and/or a structural representation (a security label) of the sensitivity of the message.This document also describes a header field, SIO-Label-History, for recording changes in the message's label.