function validateform()
{
	if (document.newsletter_subscription.to_address.value == 'o seu email' ){
		alert('Preencha o seu email.');
		document.newsletter_subscription.to_address.focus();	
	}
	else{
		var ptrn_email
		var myRegExp 
	
		ptrn_email='^[a-z][a-z_0-9\.]+@[a-z_0-9\.\-]+\.[a-z]{2,3}$'
	
		myRegExp = new RegExp(ptrn_email, 'i') 
	
		if (!myRegExp.test(document.newsletter_subscription.to_address.value)){
			alert('O email que inseriu tem um formato inválido!');
			document.newsletter_subscription.to_address.focus();
		}
		else{
			document.newsletter_subscription.action = 'subscribe.asp';
			document.newsletter_subscription.submit();
		}
	}
}