Based on your feedback/suggestion we managed to indeed create solution. We did notice however that custom js didn't work at module-settings-level. We had to use portal-settings-level (we did not try page-settings-level yet). This is a pity.
We are hoping to improve the js file to change even more settings in order to produce flawless email html. We will share those changes once we made them.
We are hoping to improve the js file to change even more settings in order to produce flawless email html. We will share those changes once we made them.