How does 'reply with history' cuts th graphics in body field?

In the original mail template, when you reply with history, the ‘body’ field inherits the ‘Memo’ form. Just like in my db. But in ‘mail’ template, it also get rid of a ‘mail header background picture’. This is not a case of my db. I see in the body field also the background picture.

How is this achieved in the mail temlate? How can I get rid of it? It’s not clear to me …