C＃SMTP套接字问题

Question

我正在编写一个测试电子邮件地址的应用程序，我需要发送少量数据到电子邮件地址以完全验证它的一部分，我目前使用套接字来实现这一点。

虽然我正在测试我使用了一个朋友的SMTP服务器进行测试，并且我的套接字工作正常，但是当我在一个大的电子邮件提供商（gmail，hotmail等）上尝试同样的事情时，却没有它。

现在我得出结论，认证和安全相关，所以我测试了使用StlEnabled内建的SmtpClient和各种Mail对象中的.Nets发送一条消息给gmail，并给它提供它要求的凭证，上班。

我需要做到的是：

，而无需提供登录信息纯粹作为交换发送这个数据。 也是一种将Ssl安全性融入到我的套接字中的方法。

任何这方面的帮助将是伟大的和appriciated！下面的代码...

/// <summary> 
    /// Opens up the socket and begins trying to connect to the provided domain 
    /// </summary> 
    /// <param name="domain">The domain listening on SMTP ports</param> 
    /// <param name="recipient">The email recipient</param> 
    /// <returns>Bool verifying success</returns> 
    public static bool ActivateSocket(string domain, string recipient) 
    { 
     //X509Certificate cert = new X509Certificate(); 

     //Prepare our first command 
     string SMTPcommand = "HELO www.codegremlin.co.uk\r\n"; 
     Encoding ASCII = Encoding.ASCII; 
     //convert to byte array and get the buffers ready 
     Byte[] ByteCommand = ASCII.GetBytes(SMTPcommand); 
     Byte[] RecvResponseCode = new Byte[3]; 
     Byte[] RecvFullMessage = new Byte[256]; 
     //method response value 
     bool TransactionSuccess = false; 



     try 
     { 
      // do all of this outside so its fresh after every iteration 
      Socket s = null; 
      IPEndPoint hostEndPoint; 
      IPAddress hostAddress = null; 
      int conPort = 587; 

      // get all the ip's assosciated with the domain 
      IPHostEntry hostInfo = Dns.GetHostEntry(domain); 
      IPAddress[] IPaddresses = hostInfo.AddressList; 

      // go through each ip and attempt a connection 
      for (int index = 0; index < IPaddresses.Length; index++) 
      { 
       hostAddress = IPaddresses[index]; 
       // get our end point 
       hostEndPoint = new IPEndPoint(hostAddress, conPort); 

       // prepare the socket 
       s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp); 
       s.ReceiveTimeout = 2000; 
       s.SendTimeout = 4000; 
       try { s.Connect(hostEndPoint); } 
       catch { Console.WriteLine("Connection timed out..."); } 

       if (!s.Connected) 
       { 
        // Connection failed, try next IPaddress. 
        TransactionSuccess = false; 
        s = null; 
        continue; 
       } 
       else 
       { 
        // im going through the send mail, SMTP proccess here, slightly incorrectly but it 
        //is enough to promote a response from the server 

        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        s.Send(ByteCommand, ByteCommand.Length, 0); 
        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        ByteCommand = ASCII.GetBytes("MAIL FROM:mamooo@gmail.com\r\n"); 
        s.Send(ByteCommand, ByteCommand.Length, 0); 
        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        ByteCommand = ASCII.GetBytes("RCPT TO:MatthewArnold@ccoder.co.uk\r\n"); 
        s.Send(ByteCommand, ByteCommand.Length, 0); 
        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        ByteCommand = ASCII.GetBytes("DATA\r\n"); 
        s.Send(ByteCommand, ByteCommand.Length, 0); 
        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        ByteCommand = ASCII.GetBytes("this email was sent as a test!\r\n.\r\n"); 
        s.Send(ByteCommand, ByteCommand.Length, 0); 
        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        ByteCommand = ASCII.GetBytes("SEND\r\n"); 
        s.Send(ByteCommand, ByteCommand.Length, 0); 
        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        ByteCommand = ASCII.GetBytes("QUIT\r\n"); 
        s.Send(ByteCommand, ByteCommand.Length, 0); 
        s.Receive(RecvFullMessage); 
        Console.WriteLine(ASCII.GetString(RecvFullMessage)); 

        int i = 0; 
        TransactionSuccess = true; 
       } 

      } 


     } 

     catch (SocketException e) 
     { 
      Console.WriteLine("SocketException caught!!!"); 
      Console.WriteLine("Source : " + e.Source); 
      Console.WriteLine("Message : " + e.Message); 
     } 
     catch (ArgumentNullException e) 
     { 
      Console.WriteLine("ArgumentNullException caught!!!"); 
      Console.WriteLine("Source : " + e.Source); 
      Console.WriteLine("Message : " + e.Message); 
     } 
     catch (NullReferenceException e) 
     { 
      Console.WriteLine("NullReferenceException caught!!!"); 
      Console.WriteLine("Source : " + e.Source); 
      Console.WriteLine("Message : " + e.Message); 
     } 
     catch (Exception e) 
     { 
      Console.WriteLine("Exception caught!!!"); 
      Console.WriteLine("Source : " + e.Source); 
      Console.WriteLine("Message : " + e.Message); 
     } 

     return TransactionSuccess; 

    } 

Answer 1

为什么你正试图自己实现这个功能？

您应该重新使用现有的SMTP实现，否则您将永远无法正确实施大量RFC的所有细节。

我建议你再看看SmtpClient类，因为它看起来完全符合你的要求。

还有一件事：你知道这个事实，你需要与gmail地址交谈的SMTP服务器不是gmail.com，对吧？您需要从DNS检索gmail.com的MX记录并连接到其中一个。

除此之外，您不应该直接连接到任何SMTP来传递邮件。如果服务器执行重定向列表和其他垃圾邮件技术，您将不会成功。依靠系统上的MTA发送电子邮件。如果您正在执行此操作来检查电子邮件地址的正确性，则需要提供一个可用的FROM地址并检查该邮箱是否从MTA中跳出。