What designation should be used for official correspondence containing matters exempt from public disclosure?

The designation that should be used for official correspondence containing matters exempt from public disclosure is "For Official Use Only," commonly abbreviated as FOUO. This designation is important because it indicates that the information is not classified at the level of "Confidential," "Secret," or "Top Secret," but still requires some degree of protection from unauthorized access or disclosure. FOUO applies to sensitive but unclassified information that, if disclosed, could cause harm to individuals or organizations, or compromise operations or activities.

Using FOUO helps ensure that those who handle the correspondence understand the need for discretion and the importance of safeguarding the information from public access. It serves to protect important details that, while not officially classified, are still sensitive in nature, reinforcing responsible information management practices within the Marine Corps and other government agencies.