public void Test163()
    {
      var imapServer = "imap.163.com";
      var port = 993;
      using (ImapClient client = new ImapClient(imapServer, port, "xxxx@163.com", "pwd", AuthMethod.Login, true))
      {
        // Returns a collection of identifiers of all mails matching the specified search criteria.
        IEnumerable<uint> uids = client.Search(SearchCondition.Unseen());
        // Download mail messages from the default mailbox.
        IEnumerable<MailMessage> messages = client.GetMessages(uids,FetchOptions.HtmlOnly);

        Console.WriteLine("We are connected!");
      }

    }

protected void Button2_Click(object sender, EventArgs e)
  {
    System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient();
    client.Host = "smtp.163.com";//使用163的SMTP服務(wù)器發(fā)送郵件
    client.UseDefaultCredentials = true; 
    client.DeliveryMethod = System.Net.Mail.SmtpDeliveryMethod.Network; 
    client.Credentials = new System.Net.NetworkCredential("用戶名", "密碼");//163的SMTP服務(wù)器需要用163郵箱的用戶名和密碼作認證，如果沒有需要去163申請個,                                     
    //這里假定你已經(jīng)擁有了一個163郵箱的賬戶，用戶名為abc，密碼為******* 
    System.Net.Mail.MailMessage Message = new System.Net.Mail.MailMessage();
    Message.From = new System.Net.Mail.MailAddress("上述用戶名密碼所對應的郵箱地址");//這里需要注意，163似乎有規(guī)定發(fā)信人的郵箱地址必須是163的，而且發(fā)信人的郵箱用戶名必須和上面SMTP服務(wù)器認證時的用戶名相同                                
    //因為上面用的用戶名abc作SMTP服務(wù)器認證，所以這里發(fā)信人的郵箱地址也應該寫為abc@163.com
    Message.To.Add("目標郵箱地址");//將郵件發(fā)送給Gmail
    //Message.To.Add("123456@qq.com");//將郵件發(fā)送給QQ郵箱
    Message.Subject = "customer feedback";
    Message.Body = "customer feedback content"; 
    Message.SubjectEncoding = System.Text.Encoding.UTF8;
    Message.BodyEncoding = System.Text.Encoding.UTF8;
    Message.Priority = System.Net.Mail.MailPriority.High;
    Message.IsBodyHtml = true;
    client.Send(Message);
  }