public static RestResponse SendSimpleMessage() {
    RestClient client = new RestClient();
    client.BaseUrl = "https://api.mailgun.net/v2";
    client.Authenticator = new HttpBasicAuthenticator(
        "api","key-3ax6xnjp29jd6fds4gc373sgvjxteol0");
    RestRequest request = new RestRequest();
    request.AddParameter("domain",
                        "samples.mailgun.org", ParameterType.UrlSegment);
    request.Resource = "{domain}/messages";
    request.AddParameter("from", "Excited User <[email protected]>");
    request.AddParameter("to", "[email protected]");
    request.AddParameter("subject", "Hello");
    request.AddParameter("text", "Testing some Mailgun awesomness!");
    request.Method = Method.POST;
    return client.Execute(request);
}