My corporation using MS Exchange for mail. I can also use O365 if that helps. I tried to export to html, and then use Outlook by attaching as text, which gets like 80% of the way, but the images get stretched out and some tables get black borders. So this isn't it.

I know I can send it from the software, but makes it show up as an external mail and gets the big EXTERNAL stamps in the subject.

Is there a way to do this from Outlook?

I think you can setup outlook to use the RED html email as a template.