-ERR超过登录限制15分钟。减少对POP3服务器的请求频率

使用以下代码，我已经从我的hotmail帐户中读取了味精。但是有时会出现以下错误。-ERR Exceeded the login limit for a 15 minute period. Reduce the frequency of requests to the POP3 server。谁能告诉我这是什么原因？那是服务器问题还是其他问题？除了pop3以外，我们可以将其他协议用于hotmail吗？

  public string hotmail(string username, string password)
  {
    string result = "";
    string str = string.Empty;
    string strTemp = string.Empty;
    try
    {
        TcpClient tcpclient = new TcpClient();
        tcpclient.Connect("pop3.live.com", 995);
        System.Net.Security.SslStream sslstream = new SslStream(tcpclient.GetStream());
        sslstream.AuthenticateAsClient("pop3.live.com");
        System.IO.StreamWriter sw = new StreamWriter(sslstream);
        System.IO.StreamReader reader = new StreamReader(sslstream);
        strTemp = reader.ReadLine();
        sw.WriteLine("USER" + " " + username);
        sw.Flush();
        strTemp = reader.ReadLine();
        sw.WriteLine("PASS" + " " + password);
        sw.Flush();
        strTemp = reader.ReadLine();
        string[] numbers = Regex.Split(strTemp, @"\D+");
        int a = 0;
        foreach (string value in numbers)
        {
            if (!string.IsNullOrEmpty(value))
            {

                int i = int.Parse(value);
                numbers[a] = i.ToString();
                a++;
            }
        }
        sw.WriteLine("RETR" + " " + numbers[0]);
        sw.Flush();
        strTemp = reader.ReadLine();
        while ((strTemp = reader.ReadLine()) != null)
        {
            if (strTemp == ".")
            {
                break;
            }
            if (strTemp.IndexOf("-ERR") != -1)
            {
                break;
            }
            str += strTemp;
        }
        sw.WriteLine("Quit ");
        sw.Flush();
        result = str;
        return result;
     }
     Catch ( Exception ex)
     {}
     return result;
  }

提前致谢 ..