[Doofer]

Unless things have changed since I was in the military the overall classification will be at the top and bottom of a document or message and it will be spelled out.

If a paragraph or sentence is classified, it will have a (c) proceeding the text for Confidential.

[Doofer]

If it’s classified higher it will have a single letter indicating it’s classification.

[exDemMom]

Each paragraph has a letter(s) to indicate its classification. Her emails most likely contained paragraphs cut/pasted from documents.