Hello again. Thanks, that seems to work. The emails are now delivered.
The new problem which arose, however, is that each time the user submits the form with their message, instead of getting the response that everything went right or not at the bottom, they are being redirected to the Contact page with Ajax off.
Any news please? As I have mentioned this is a very serious problem. If it cannot be resolved, I would not really like to use your product. Not having a proper contact form is just unjustifiable.