Almost...
I've tried adding the EMAIL_BODY_HTML_EDITOR.StyleText code to a few places within the js of InEmail, e.g. PopulateMessage, setHTMLEditorFormat. Doing this means when the email in displayed within the popup Send Email window the formatting now looks right. Unfortunately when you send the email, the style is not included so the recipient does not see the styling - as attached.
Within Outlook I've clicked to View Source of the email received and the results are attached. It's only including the code from the:
<DIV iwtype="Messaging-section-richtext" iwprotected="true"> line down.
Any other idea's if there is a way round this?