The GetItemValue method of the Document class returns rich-text item values as an array of strings, with all rich text styling removed. The "body" field in a Notes email is generally rich text. So, you should look into using the GetFirstItem method, instead. That will return a NotesRichTextItem object (for the body field). From that object, you can access the styling of the text, hyperlinks and file attachments, etc. (I do not believe that you can access in-line images at all via the "back-end" COM classes - I think for that, you will need to drop down to use the C API classes).
Here's a quick sample of how to get a NotesRichTextItem handle:
Dim doc As NotesDocument
Dim rtitem As Variant
... get the document
Set rtitem = doc.GetFirstItem( "Body" )
If rtitem.Type = RICHTEXT Then
.. work with rtItem
End If
Here is the doc page for the NotesRichTextItemClass:
http://publib-b.boulder.ibm.com/lotus/c2359850.nsf/2e73cbb2141acefa85256b8700688cea/dc72d312572a75818525731b004a5294?OpenDocument
And here is a starting point for the C API docs:
http://www14.software.ibm.com/webapp/download/nochargesearch.jsp?k=ALL&S_TACT=104CBW71&status=Active&q=Lotus+%22C+API%22