Hi Scott,
fyi, I just posted a new release of Form Wizard Pro, it requires also upgrading to the new release of mojoPortal 2.3.9.8. This issue should be fixed in the new version. Now there is full control over the email template so it can be customized and configured for using either plain text or html email. Look in the settings after upgrading to find the new settings for custom email templates with a link to edit them.
Hope that helps,
Joe