function isValidEmail(str) {
	return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);
}

$(document).ready(function() {

	$('#submitbutton').click(function() {
		var email = $("#email").val();

		if( isValidEmail(email) ){
			$("#submitbutton").disabled = true;
			$("#progress").css('visibility', 'visible');

			$("#maillistForm").load('addemail.php', {email: email});

		} else {
			alert("Please enter a valid e-mail address");
		}

		return false;
	});

});