1. using System; 
  2. using System.Collections.Generic; 
  3. using System.ComponentModel; 
  4. using System.Data; 
  5. using System.Drawing; 
  6. using System.Text; 
  7. using System.Windows.Forms; 
  8. using System.Net; 
  9. using System.Net.Sockets; 
  10. namespace SendMail 
  11. { 
  12.     public partial class Form1 : Form 
  13.     { 
  14.         public Form1() 
  15.         { 
  16.             InitializeComponent(); 
  17.         } 
  18.         private void button1_Click(object sender, EventArgs e) 
  19.         { 
  20.             for (int i = 0; i < 20; i++) 
  21.             { 
  22.                 string[] recs = rec.Text.Split(';'); 
  23.                 bool isyes = SendMail(server.Text, 25, this.txt_account.Text, recs, this.subject.Text, this.content.Text, true, this.txt_pwd.Text); 
  24.             } 
  25.             //if (isyes) 
  26.             //{ 
  27.             //    MessageBox.Show("邮件发送成功"); 
  28.             //} 
  29.         } 
  30.         NetworkStream ns; 
  31.         /// <summary> 
  32.         ///  
  33.         /// </summary> 
  34.         /// <param name="smtpServer">smtp服务器</param> 
  35.         /// <param name="point">发送端口</param> 
  36.         /// <param name="_from">发件人</param> 
  37.         /// <param name="_tos">收件人</param> 
  38.         /// <param name="_subject">主题</param> 
  39.         /// <param name="_content">内容</param> 
  40.         /// <param name="isESMTP">是否需要身份验证</param>        
  41.         /// <param name="userPWD">发件人密码</param>        
  42.         /// <returns></returns> 
  43.         public bool SendMail(string smtpServer, int point, string _from, string[] _tos, string _subject, string _content, bool isESMTP, string userPWD) 
  44.         { 
  45.             try 
  46.             { 
  47.                 TcpClient smtpClient = new TcpClient(); 
  48.                 IPAddress ip = Dns.GetHostAddresses(smtpServer)[0]; 
  49.                 smtpClient.Connect(ip, point);//连接服务器 
  50.                 ns = smtpClient.GetStream(); 
  51.                 if (SMTPReceive() != 220) 
  52.                     return false; 
  53.                 Send("HELO\r\n"); 
  54.                 if (SMTPReceive() != 250) 
  55.                     return false; 
  56.                 //身份验证 
  57.                 if (isESMTP) 
  58.                 { 
  59.                     Send("AUTH LOGIN\r\n"); 
  60.                     if (SMTPReceive() != 334) 
  61.                         return false; 
  62.                     string uname = _from.Substring(0, _from.IndexOf('@')); 
  63.                     Send(ConvertToBase64(uname) + "\r\n"); 
  64.                     if (SMTPReceive() != 334) 
  65.                         return false; 
  66.                     Send(ConvertToBase64(userPWD) + "\r\n"); 
  67.                     if (SMTPReceive() != 235) 
  68.                         return false; 
  69.                 } 
  70.                 Send("Mail From:<" + _from + ">\r\n");//发件人 
  71.                 if (SMTPReceive() != 250) 
  72.                     return false; 
  73.                 if (_tos.Length < 0) 
  74.                     return false; 
  75.                 foreach (string to in _tos) 
  76.                 { 
  77.                     Send("RCPT TO:<" + to + ">\r\n"); 
  78.                     if (SMTPReceive() != 250) 
  79.                         return false; 
  80.                 } 
  81.                 Send("DATA \r\n"); 
  82.                 if (SMTPReceive() != 354) 
  83.                     return false; 
  84.                 StringBuilder content = new StringBuilder(); 
  85.                 content.Append("From:" + _from + "\r\n"); 
  86.                 if (_tos.Length <= 0) 
  87.                     return false; 
  88.                 foreach (string to in _tos) 
  89.                 { 
  90.                     content.AppendFormat("To:{0}\r\n", to); 
  91.                 } 
  92.                 //邮件标题 
  93.                 content.AppendFormat("Subject:{0}\r\n", _subject); 
  94.                 //邮件编码格式 
  95.                 content.AppendFormat("Charset=\"{0}\"\r\n", "gb2312"); 
  96.                 content.Append("\r\n"); 
  97.                 content.Append(_content);//追加发送的内容 
  98.                 content.Append("\r\n.\r\n"); 
  99.                 Send(content.ToString()); 
  100.                 if (SMTPReceive() != 250) 
  101.                     return false; 
  102.                 else 
  103.                     return true; 
  104.             } 
  105.             catch (Exception exc) 
  106.             { 
  107.                 return false; 
  108.             } 
  109.         } 
  110.         /// <summary> 
  111.         /// 将string型转换为Base64 
  112.         /// </summary> 
  113.         /// <param name="str"></param> 
  114.         /// <returns></returns> 
  115.         string ConvertToBase64(string str) 
  116.         { 
  117.             byte[] data = Encoding.UTF8.GetBytes(str); 
  118.             return Convert.ToBase64String(data); 
  119.         } 
  120.         /// <summary> 
  121.         /// 发送消息至服务器  
  122.         /// </summary> 
  123.         /// <param name="msg"></param> 
  124.         public void Send(string msg) 
  125.         { 
  126.             byte[] data = Encoding.UTF8.GetBytes(msg); 
  127.             ns.Write(data, 0, data.Length); 
  128.             ns.Flush(); 
  129.         } 
  130.         public int SMTPReceive() 
  131.         { 
  132.             try 
  133.             { 
  134.                 byte[] data = new byte[1024]; 
  135.                 int size = ns.Read(data, 0, 1024); 
  136.                 string result = Encoding.UTF8.GetString(data, 0, size); 
  137.                 int index = result.IndexOf(' '); 
  138.                 if (index == -1) 
  139.                     index = result.Length; 
  140.                 result = result.Substring(0, index); 
  141.                 return int.Parse(result); 
  142.             } 
  143.             catch 
  144.             { 
  145.                 return 0; 
  146.             } 
  147.         } 
  148.     } 
  149. }