var reEmail = /^([a-zA-Z0-9_\.\-\+])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/
function isValidEmail(email){
    if(reEmail.test(email)){
        return true;
    }else{
        return false;
    }
}
function TestNewsletter(id){
    if( isValidEmail(document.getElementById(id).value) ){
        return true;
    }else{
        alert("Erreur : adrersse email invalide!");
        return false;
    }
}