What you want cannot be done. Most e-mail clients don't show it this way, but TB shows attachments this way. An image included in a message is always sent as an attachment. Same goes for html formatted stuff. E-mail is originally text based and with its display TB is true to that. But like I said, other clients won't show it like that.
__________________________________ I'm just a user of The Bat! I don't work for Ritlabs.