Offering a form to your contacts is a good idea, as it allows you, among other functions, to learn more about them and subsequently maintain an increasingly personalized relationship.
That said, for this personalization to be possible, your audience must express its consent and confirm it. This is what is called double opt-in.
When creating your form, after choosing your template, simply click on the selector “Activer la demande de confirmation (double opt-in)”.
Once your form has been created, your contact will receive an email requesting confirmation of their subscription. It is this acceptance that gives you authorization to fully use the data they have entrusted to you by completing the form.