Improve Word HTML rendering in email
It's absolutely crazy that in Outlook 2016 we still can't use fundamental parts of the original CSS spec in HTML-based email templates. I'm specifically referring to float, padding, and background-image. It would also be nice to not have to build HTML emails using tables so that they can be responsive.
It's fine by me if Outlook continues to use Word to create/author HTML-based emails, because that's what Outlook users are used to using. However, the display of incoming HTML-based emails should be rendered by a real HTML engine, not Word, especially if those incoming emails weren't originally created in Outlook/Word, such as newsletters sent from MailChimp and similar services.
Aaron Marks commented
HTML rendering of emails is broken currently. I'm not sure if emails are being rendered with Word's HTML engine still, but they should instead be rendered with a modern HTML engine like what IE and Edge use.
Gmail, mobile devices, and even the Universal Mail app don't have problems rendering HTML Emails but Outlook does.