When a contact has the "Do Not Allow" flag set to Yes for Email, and an attempt is made to send that contact an email, an ugly error message is displayed. For our business users who are not technical, this is a very bad experience. It should instead display a subtle message, like in the pink/red bar above the form instead of a pop-up, that says the email can't be sent because the contact doesn't currently want to receive emails (or something to that effect). The bottom line--make it user friendly, not technical and vague.