I'm not exactly clear what the problem is. When you "copy and paste", are you copying HTML as if it were text, or copying from a webpage? If you are copying from a webpage, it is being translated into rich text, and then the rich text must be translated back into HTML. That will work to some degree, but two conversions is likely to lose a fair amount. From Outlook, you are sending the HTML mail itself. It is somewhat like taking a message in English and translating to Turkish and then back to English. No matter how good the translation, you will lose some information. Unfortunately, this translation isn't even that good, since the HTML->RT translation loses almost all CSS, and the RT->HTML translation does a fairly sloppy job of handling tables and graphics and such.
There are different solutions to this. You can send true HTML e-mail either by building the MIME parts yourself using the Notes 6 NotesMIMEEntity classes, or by using a product like our
Midas Rich Text LSX with the
Send It! demo to send HTML.
If you don't want to go with the approach of actually sending HTML, you can clean up the imported HTML in rich text to at least do a better approximation of the original, and save it, close and open the e-mail, which will eliminate the vestiges of the original HTML so that you are really doing only the RT->HTML portion. Not great, but better than what you get if you just copy/paste/send.