function valid_email(emailAddress)
{
	var bRet = true;
	if ( emailAddress.length > 0 )
	{
		var email=/^[A-Za-z0-9]+([_\.-][A-Za-z0-9]+)*@[A-Za-z0-9]+([_\.-][A-Za-z0-9]+)*\.([A-Za-z]){2,4}$/i;
		if ( !email.test(emailAddress) )
		{
			bRet = false;
		}
	}
	
	return bRet;
}