function verify_email(f) {
	if(isBlank(f.email.value) || (!isValidEmail(f.email.value))) {
		alert('Please enter a valid email address');
		return false;
	}
	alert('Your email has been submitted.');
	return true;
}

function isBlank(s) {
	for (var i = 0; i < s.length; i++) {
		var c = s.charAt(i);
		if ((c != " ") && (c !=  "\\n") && (c != "\\t")) return false;
	}
	return true;
}

function isValidEmail(email) {
	var email1 = /(@.*@)|(\.\.)|(@\.)|(\.@)|(^\.)/;
	var email2 = /^.+\@(\[?)[a-zA-Z0-9\-\.]+\.([a-zA-Z]{2,3}|[0-9]{1,3})(\]?)$/;
	if ((email1.test(email) == true) || (email2.test(email) == false) && (email != "")) {
		return false;
	}
	return true;
}