Thanks for the answer,
the form attribute is the same, it’s correct. In fact the mechanism works correctly, I receive the confirmation email and the email address entered is added to the newsletter list.
The problem is that in the web page I don’t receive any notification, procedure that works correctly if I use the basic form.
The oddity is that I just copied and pasted the base form into the editable form 1 without changing anything.
I do not explain this.