An electronic signature on a document becomes valid upon its submission. Pursuant to Art. 61 §2 of the Civil Code: "The declaration of will expressed in electronic form is submitted to another person at the moment when it is entered into the means of electronic communication in such a way that the person can read its content."
Both national and European law do not necessarily require signatures to always be on paper and do not discriminate or deny validity of the electronic form. According to civil law: "Subject to the exceptions provided for in the Act, the will of a person performing a legal transaction may be expressed by any behavior of that person that discloses their will in a sufficient manner, including by disclosing that will in an electronic form" (Art. 60 of the Civil Code).
It is worth noting that only a few types of documents require a special form, and even when they do require such a form, failure to do so does not always invalidate a given signing act. It is also worth remembering that even if a written form is required for the validity of a given activity, it can be replaced by an electronic form by placing a qualified electronic signature under the document (cf. 781 § 2 of the Civil Code).