What is the difference between a beautiful coloured and designed HTML e-mail and the text equivalent?

In a recent N4B.COM mail out the difference between a campaign response from a HTML e-mail and a text version was some 300%. This number will horrify some Internet purists but the fact is people respond more positively to things that look good. The TurnKey Newsletter module plugs in to the TurnKey Mail List Manager to allow site owners to build HTML and multi part mime e-mails through their web browser. The Mail List Manager allows you to send them and the Tracker Module lets you monitor the response.