平时发验证码邮件都是用免费域名邮箱，但是有时一频繁发多了就发不了了，听说用sendcloud可以避免，还能避免阿里云邮件发QQ邮箱进垃圾箱中，去注册了下，免费账户号每个月才50封，自己玩玩可以吧。。

收费的话一个月59，1万封以内的，不知道行不行。。先看看吧。。

下面是封装好的代码，那个api_user和api_key进网页里设置就好了

    /*

• SendMailBySendCloud
• 功能：使用SendCloud发送邮件
• 返回值：string，JSON格式的返回值，或者异常
• 参数：
• from - 显示的发件人邮箱
• to - 收件人邮箱
• title - 邮件标题

• content - 邮件内容
  */
  public static string SendMailBySendCloud(String from, String to, String title, String content, string api_user = "niuna?????", string api_key = "v2?????")
  {
  String url = "http://api.sendcloud.net/apiv2/mail/send";
  HttpClient client = null;
  HttpResponseMessage response = null;
  string result;

      try
      {
  
          client = new HttpClient();
  
          List<KeyValuePair<String, String>> paramList = new List<KeyValuePair<String, String>>();
  
          paramList.Add(new KeyValuePair<string, string>("apiUser", api_user));
          paramList.Add(new KeyValuePair<string, string>("apiKey", api_key));
          paramList.Add(new KeyValuePair<string, string>("from", from));
          paramList.Add(new KeyValuePair<string, string>("fromName", from));
          paramList.Add(new KeyValuePair<string, string>("to", to));
          paramList.Add(new KeyValuePair<string, string>("subject", title));
          paramList.Add(new KeyValuePair<string, string>("html", content));
  
          response = client.PostAsync(url, new FormUrlEncodedContent(paramList)).Result;
          result = response.Content.ReadAsStringAsync().Result;
          //Console.WriteLine(result);
      }
      catch (Exception e)
      {
          result = e.Message;
          Console.WriteLine("\nException Caught!");
          Console.WriteLine("Message :{0} ", e.Message);
      }
      finally
      {
          if (null != client)
          {
              client.Dispose();
          }
      }
  
      return result;
  }