function sendMail(url, params, func, optional_query) {
    var api_url = '/api/mailer/' + url + '/';
    if (optional_query) {
        api_url += optional_query;
    }

    new Ajax.Request(api_url , {
        method: "post",
        parameters: makeParameter(params),
        onSuccess: func
    });
}

function makeParameter(params) {
    var arr = new Array();
    for (var param_key in params) {
        arr.push(param_key + '=' + params[param_key]);
    }
    return arr.join('&');
}