No, you've got it all wrong. There IS a plugin. Go to Apps in the finder, then select mail and control-click (right-click). Then press get info. And scroll down to Plug-ins. See I accidently deleted that plugin and that plugin, is an attatchment plugin. How do I get it back? This is what an attatchment looks like when I attatch an attchment. (its attatched to the post).
And yes you're seeing the image properly that what an attachment looks like in my mail. A LEGO brick with question marks. I repeat, Can someone help?