Email Client template body type needs to be HTML to avoid character translations or extra ReturnsProblem
String fields and HTML fields hold data in different formats. The client template requires the body to be HTML type to avoid having to translate from string to HTML.
You will fine extra returns on the email client body. Also, some data will be truncated if double angle-bracket tags <<>> are used.
Email client body type is HTML and anything else will be translated into this format.