function waliduj(){
var validValue = 1;
var default_text = "Wpisz swój e-mail!";
var strEmail = document.getElementById("newsletter_mail").value;
var pustePole = 1;
  validRegExp = /^[^@]+@[^@]+.[a-z]{2,}$/i;   

   // search email text for regular exp matches
    if (strEmail.search(validRegExp) == -1 || strEmail == default_text) 
   {
      if(lang_text.i == "pl")
      {
      document.getElementById("newsletter_mail").value = "Nieprawidłowy e-mail";
      setTimeout(function() {
      document.getElementById("newsletter_mail").value = "Wpisz swój e-mail";
      }, 2500);
      }
      if(lang_text.i == "en")
      {
      document.getElementById("newsletter_mail").value = "Invalid email address";
      setTimeout(function() {
      document.getElementById("newsletter_mail").value = "Put your e-mail";
      }, 2500);
      }
      
      validValue = 0;
    } 
    else {
    document.getElementById("newsletter_baltona_form").submit();
    }

}