What is a requirement for instant messages that are retained for classification purposes?

For instant messages that are retained for classification purposes, having a banner marked at the top and bottom is essential. This marking serves to indicate the classified status of the communication clearly and ensures that anyone who accesses the message is immediately aware of its classification level. The banner acts as a critical visual cue that helps maintain awareness and compliance with the legal and procedural requirements concerning the handling of classified information.

By marking the top and bottom of the message, it reinforces the importance of the information contained within and protects it accordingly. This is particularly vital in environments where multiple forms of communication are used and where the potential for accidental dissemination of sensitive information exists.

The other options present approaches that do not align with the necessary protocols for handling classified instant messages. For instance, deleting messages after a short duration does not account for the need to retain classified communications as prescribed by regulations, while partial marking at least at the end does not adequately convey the classified nature of the content. Sharing only with the originating activity may limit the accessibility needed for proper information management and accountability regarding classified data.