In mail.app, pdf attachments can be viewed as icons or as inline documents, complete with their own scroll bars if necessary. Toggling between the two views is easy via the contextual menu (right-clicking on the attachment).
I know that DT/DN allows such view switching globally via the application preferences. Is it possible, however, to select the view type independently for each attachment? Unfortunately, right-clicking on a pdf attachment does not yield a contextual menu.