Posting an attachment to the outbound_email end point I am trying to use RestSharp to call the outbound_email endpoint.If I don’t include an attachment I am able to post to the end point successfully, however when I do include an attachment using the code below it fails. var client = new RestClient(outboundEmail); var request = new RestRequest("", Method.Post); request.AddHeader("Authorization", "Basic " + Convert.ToBase64String(Encoding.Default.GetBytes(apiKey + ":X"))); string attachmentFilePath = filePath; byte[] attachmentBytes = File.ReadAllBytes(attachmentFilePath); request.AddHeader("Accept", "application/json"); request.AddHeader("Content-Type", "multipart/form-data"); request.AddFile("attachments[]", attachmentBytes, file.pdf, "application/pdf"); request.AddParameter("email", myEmail); request.AddParameter("subject", subject); request.AddParameter("des