public static string CreateTimeoutTestMessage(string server) 
{ 
 string Success = "发送成功"; 
 try 
 { 
     string _to = "1035092449@qq.com"; 
     string _from = "young-20@163.com"; 
     string _subject = "Using the new SMTP client."; 
     string _body = @"Using this new feature, you can send an e-mail message from an application very easily."; 
     MailMessage message = new MailMessage(); 
     message.From = new MailAddress(_from); 
     //可以利用MailMessage.To.Add方法增加要发送的邮件地址 
     message .To .Add (new MailAddress ("652105072@qq.com")); 
     message.To.Add(new MailAddress(_to)); 
     message.Subject = _subject; 
     message.Body = _body; 
 
     //添加附件 
     Attachment a = new Attachment(@"C:/Users/Administrator/Desktop/smtpclient.rar"); 
     message.Attachments.Add(a); 
     //设置邮箱的地址或IP 
     SmtpClient client = new SmtpClient(server); 
     //设置邮箱端口，pop3端口:110, smtp端口是:25  
     client.Port = 25; 
      
     //设置超时时间 
     client.Timeout = 9999; 
      
     //要输入邮箱用户名与密码 
      
     client.Credentials = new NetworkCredential("young-20@163.com", "******"); 
     client.Send(message); 
 } 
 catch (Exception ex) 
 { 
     Success = ex.ToString(); 
 } 
 return Success; 
} 

try 
{
     SmtpClient client = new SmtpClient(); 
     client.Host = "smtp.qq.com"; 
     MailMessage mm = new MailMessage(); 
     client.Port = 25; 
      
     mm.From = new MailAddress("652105072@qq.com");      
     mm.To.Add(new MailAddress("1035092449@qq.com")); 
     mm.Subject = "Hello~!"; 
     mm.Body = "HIthere.here is a post "; 
     mm.IsBodyHtml = false; 
     mm.Priority = MailPriority.High; 
 
     client.Credentials = new NetworkCredential("652105072@qq.com", "******"); 
     client .Send (mm);
 } 
 catch (Exception ex) 
 { 
     MessageBox.Show(ex.Message); 
 }