Outlook 2003: Email attachment appears in the main body

After our Email server upgrade to Exchange 2007, I suddenly found my email attachment show up in the main body as an icon when I use outlook 2003. It used to appear in the attachment line under the subject line. It annoys me a little bit, yep, I agree, this format is useful in some cases, but I don't like it, I prefer the attachment is in its place and not mess up the layout. I look at the email, and find the Email format has been changed to "Rich Text", I remember it was "HTML". The setting should be in somewhere.

Yeap, I find it. Click menu "tools"->"options", click "Mail Format", in "Message format" section, select "HTML", apply it. now everything goes back.