reqFTP = (FtpWebRequest)FtpWebRequest.Create(new Uri("ftp:...../inbox/" + fileName));
reqFTP.Method = WebRequestMethods.Ftp.UploadFile;
reqFTP.UsePassive = true;
reqFTP.UseBinary = true;
reqFTP.KeepAlive = true;
reqFTP.ServicePoint.ConnectionLimit = files.Length;
reqFTP.Credentials = new NetworkCredential("username", "password");
reqFTP.EnableSsl = true;
ServicePointManager.ServerCertificateValidationCallback = Certificate;

System.Net.ServicePointManager.ServerCertificateValidationCallback = ((sender, certificate, chain, sslPolicyErrors) => true);