This is quite a big project by one simple reason: it's not a problem to parse e-mail and decode each of its parts. The problem is different: you need to support and render each and every MIME type which can be embedded or alternatively embedded (there are different "content dispositions"), and the number of them is pretty big. For example, you will need to support all graphics formats standardized as different MIME types, and that means all container formats and all compression formats which are not indicated in MIME line. Besides, you will need to support whole HTML, RTF and more.
(Please see
http://en.wikipedia.org/wiki/MIME[
^].)
So, just two ideas: you can use for rendering the component
WebBrower
.
Another alternative is this HTML renderer based on
RichTextBox
offered in this CodeProject article, a very good one:
A Professional HTML Renderer You Will Use[
^].
—SA