function polecstrone(){
	var email = document.getElementById('email');
	if(!isValidEmail(email.value)){ alert('Podaj poprawny adres e-mail!'); return false;}
	var form = document.getElementById('form');
	form.submit();
}
function polecstrone_en(){
	var email = document.getElementById('email');
	if(!isValidEmail(email.value)){ alert('Provide a valid e-mail!'); return false;}
	var form = document.getElementById('form');
	form.submit();
}

function isValidEmail( email ){
	var filter = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	if (!filter.test(email)) {
		return false;		
	}
	return true;	
}