Ah no wonder that's an old version which doesn't always enable HTML... Sergey had shared his sources and based on his latest source I had built an updated memailsettings...Uninstall the one you have from Store and install this version instead... Once you enable full mime in easy tweak mode go to edit settings and edit those two email/email_mime and email_mime to TRUE; remember to click Set before exiting the applet and re-sync...