Hi Cheryl - You know - you might need a mix of modules and a little bit of thought to do this..

I do not know any module off the shelf that will allow you to do this - but perhaps a mix might help.

DotNetNuke doesn't quite work the way that an 'online newsletter' would.  Your clerical staff would require some training - it's not going to be that easy unless you invest alot in a truly intuitive solution.  There are some off the shelf email modules - how they work I'm not really 100% impressed with at the moment, and that's coming from a background in email marketing, where I also have an email application currently being converted to DNN in a joint venture. 

I would look at something like the articles module from http://www.ventrian.com  which allows you to provide articles which can be quite cleverly categorised - I used this quite a bit and even in intranets where we're trying to cut back the amount of pages modules within a site for ones that will have alot of depth to them over time.  Sites with thousands of tabs and modules can be hard to keep track of.. and the articles module in my opinion is generic enough, able to be customised enough to provide the solutions alot of people are looking for. It also has a 'latest news' module that allows you to put links to articles within other pages.

There is another interesting module I've been looking at - it's an announcements module.  It's easy to use and could create nice categories for you, and sends out email with short snippets, and links to the articles - it's quite an effective module and allows to send attachments - http://www.interactivewebs.com.au/announceit/Home/tabid/76/Default.aspx  but I don't think it will allow you to format the newsletters as per your guideslines.. you might need to compromise somewhere.

I tend to create a single master html file - and then place that in the correct way.

I think there is a little bit of thought required here, perhaps the email modules are more advanced (the ones that exist) but I''ve found so many things cumbersome to use that it drives me mad.. and I'm supposed to be experienced, so I really try hard to think of ways to simplify processes but you might find that you can get a work around.. but nothing I have found is intuitive enough for people to use without some level of training, assistance, guidance, whatever it takes to get used to the framework, the shortcomings, the amazing things it does do and then mix that into the way people think and how developers think people think..   Something's got to give..

I do like what you want to achieve, so I'll give it some more thought, perhaps others here might have a brilliant answer that I can also lend  .

Nothing concrete I'm sorry - just things to look at -

Nina Meiers