function validate(newsletter_form, inp_nws) {
   var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
   var address = document.forms[newsletter_form].elements[inp_nws].value;
   if(reg.test(address) == false) {
      alert('Παρακαλώ εισάγεται έγκυρο e-mail');
      return false;
   }
}