using System;  using System.Collections.Generic;  using System.Linq;  using System.Text;  using System.Net.Mail;  using System.Net.Mime;  using System.IO;  using System.Net;    namespace _11发送电子邮件  {      class Program      {          static void Main(string[] args)          {              Console.WriteLine("用户名");              string uid = Console.ReadLine();//发件人邮箱地址@符号前面的字符tom@dddd.com,则为"tom"              Console.WriteLine("密码");//发件人邮箱的密码              string pwd = Console.ReadLine();              for (int i = 0; i < 20; i++) //连发20封，嘿嘿              {                  MailAddress from = new MailAddress("发件人的邮箱地址");                  MailAddress to = new MailAddress("收件人的邮箱地址");                  MailMessage mailMessage = new MailMessage(from, to);                  mailMessage.Subject = "Test";//邮件主题                  mailMessage.Body = "Hello, world!!";//邮件正文                    //添加附件                    string file1 = "test.txt";                  Attachment attachment1 = new Attachment(file1, MediaTypeNames.Text.Plain);                  //为附件天剑时间信息                  ContentDisposition disposition1 = attachment1.ContentDisposition;                  disposition1.CreationDate = File.GetCreationTime(file1);                  disposition1.ModificationDate = File.GetLastWriteTime(file1);                  disposition1.ReadDate = File.GetLastAccessTime(file1);                  mailMessage.Attachments.Add(attachment1);                    string file2 = "test.doc";                  Attachment attachment2 = new Attachment(file2);                  //为附件添加时间信息                  ContentDisposition disposition2 = attachment2.ContentDisposition;                  disposition2.CreationDate = File.GetCreationTime(file2);                  disposition2.ModificationDate = File.GetLastWriteTime(file2);                  disposition2.ReadDate = File.GetLastAccessTime(file2);                  mailMessage.Attachments.Add(attachment2);                    //实例化SmtpClient                  SmtpClient smtpClient = new SmtpClient("smtp.yeah.net", 25);                  //设置验证发件人身份的凭据                  smtpClient.Credentials = new NetworkCredential(uid, pwd);                  //发送                  smtpClient.Send(mailMessage);                    Console.WriteLine("OK - [{0}]",i);              }                Console.ReadKey();          }      }  }