sendwithus csharp example.cs

// 1) Set your API key
string api_key = "YOUR API KEY";

// Let's create a request
string url = "https://api.sendwithus.com/api/v1_0/send";
var httpWebRequest = (HttpWebRequest)WebRequest.Create(url);
httpWebRequest.ContentType = "text/json";
httpWebRequest.Method = "POST";

// set headers with api key
WebHeaderCollection headers = httpWebRequest.Headers;
headers.Add("X_SWU_API_KEY:" + api_key)

using (var streamWriter = new StreamWriter(httpWebRequest.GetRequestStream()))
{
    // 2) Set the data for request
    string json = new JavaScriptSerializer().Serialize(new
        {
            email_id = "EMAIL_ID",                  // required, id of email in sendwithus
            recipient = new {                       // required, recipient information
                address = "[email protected]",  // required
                name = "Customer Name"              // optional
            },
            sender = new {                          // optional
                address = "[email protected]",       // required if sender set
                name = "From Name",                 // optional
                reply_to = "[email protected]"      // optional
            }
        });

    streamWriter.Write(json);
    streamWriter.Flush();
    streamWriter.Close();

    var httpResponse = (HttpWebResponse)httpWebRequest.GetResponse();
    using (var streamReader = new StreamReader(httpResponse.GetResponseStream()))
    {
        var result = streamReader.ReadToEnd();
        // 3) Sample response (JSON)
        /*
        {
            "success" : true,
            "status" : "OK",
            "receipt_id" : "unique-receipt-id",
            "email" : {
                "name" : "Welcome New User!",
                "version_name" : "My First Version"
            }
        }
        */
    }
}

I am getting "The remote server returned an error: (400) Bad Request."
I have filled the proper API key