String.prototype.trim = function()
{
	return this.replace(/(^\s*)|(\s*$)/g,'');
}
function checkemail(email) {
	var re_deny = /(@.*@)|(\.\.)|(^\.)|(^@)|(@$)|(\.$)|(@\.)/;
	var re_dn = /^.+\@[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,4}$/;
	var re_ip = /^.+\@\[(((1?[0-9])?[0-9])|(2[0-4][0-9])|(25[0-5]))(\.(((1?[0-9])?[0-9])|(2[0-4][0-9])|(25[0-5]))){3}\]$/;
	return( ! re_deny.test(email) && ( re_dn.test(email) || re_ip.test(email) ) );
}