function check_email(evt) {
	isemail=/^.+@.+\..{2,3}$/;
	var mail=document.newsletter_form.email.value;
	var verimage=document.newsletter_form.verimage.value;
	var x=0;
	
	if (mail=='' || mail=='inserisci la tua email' || !(isemail.test(mail))) {
		document.newsletter_form.email.style.background='rgb(0,54,109)';
		document.newsletter_form.email.style.color='white';
		x=1;		
	}
	
	if (x=="1"){
		alert("devi inserire una email valida");
		stop_action(evt);
	}
	
	if (x=="0"){
		if (verimage==""){
			alert("digita i caratteri dell'immagine");
			stop_action(evt);
		}
	}
}

function stop_action(evt){		
	var bMoz = (navigator.appName == 'Netscape');	
	if (bMoz){
		evt.preventDefault();			
	}else{
		event.returnValue=false;
		return false;
	}		
}