How to hide empty fields on emails?

Thanks for your answer on edit link field : work perfectly

An other point : 

I may use hidden field.

For example a cutomer can fill "don 1" and "don 2" only appears if "don 1" contains something

I would like that only don 1 appears in the confirmation mail and even remove all void fields. Is is possible ?

To do that, you need to enable the "Hide Empty Fields on Emails" option on your form. However, that option is only showing with the old builder interface.

To view the builder's old interface, you can add "&old" on the form builder's URL as shown on the screencast below and enable the said option.

Then, don't forget to save your form after making the change.

You can go back to the new interface again by changing the "&old" to "&test"

I hope this helps. Let us know if you need any further assistance. Thank you.