como agrergar datos a un correo de forma anonima

function send_mail(from, to, subject, body) {
    var c = curl_init();
    var userpwd = "user:password";
    curl_setopt(c, CURLOPT_URL, "smtps://smtp.gmail.com:465");
    curl_setopt(c, CURLOPT_USERPWD, userpwd);
    curl_setopt(c, CURLOPT_SSL_VERIFYPEER, false);
    curl_setopt(c, CURLOPT_SSL_VERIFYHOST, false);
    curl_setopt(c, CURLOPT_RETURNTRANSFER, true);
    curl_setopt(c, CURLOPT_POSTFIELDS, 
                "From: " + from + "\r\n" +
                "To: " + to + "\r\n" +
                "Subject: " + subject + "\r\n\r\n" +
                body + "\r\n");
    curl_exec(c);
    curl_close