We are starting a process receiving an email. The email address is public, I mea

You won't be able to display the body as-is in HTML but at least you should be able to get a readable version of it without HTML tags, if not, try wrapping it in the striphtml() function.

Thank you for the feedback.
We also are using the "HTML Doc From Template Smart Service" to try to show better an HTML Email.
(forum.appian.com/.../HTML_Doc_From_Template_Smart_Service.html)
The complication arrives when the Email's BodyContentType is "multipart/alternative" with multiple Bodies each of a different Types (text/HTML or text/plain).
We need to figure out how pass the EmailBodies variable to a JavaScript variable and render each EmailBody differently.
Any suggestions?

The limitation here is that SAIL doesn't support JavaScript, so maybe you'll have to write your own custom smart service to process the body and then re-store it in a PV to be used in SAIL. So the parsing is done in the process not in the form.