如何從/發送電子郵件到yahoo gmail pop3等任何電子郵件地址？

我現在嘗試的是將電子郵件發送到我自己的Gmail帳戶，但是到目前爲止，我嘗試發送時遇到了錯誤。如何從/發送電子郵件到yahoo gmail pop3等任何電子郵件地址？

我沒有嘗試還沒有發到我的POP3電子郵件，而不是雅虎或從我的POP3或從雅虎。現在我試圖發送到我的Gmail。

在一個按鈕單擊事件：

private void button1_Click(object sender, EventArgs e) 
{ 
    sendit("[email protected]"); 
}

則在該方法sendit使用斷點它總是讓到catch部分

public string sendit(string ReciverMail) 
{ 
     MailMessage msg = new MailMessage(); 

     msg.From = new MailAddress("[email protected]"); 
     msg.To.Add(ReciverMail); 
     msg.Subject = "Hello world! " + DateTime.Now.ToString(); 
     msg.Body = "hi to you ... :)"; 
     SmtpClient client = new SmtpClient(); 
     client.UseDefaultCredentials = true; 
     client.Host = "smtp.gmail.com"; 
     client.Port = 587; 
     client.EnableSsl = true; 
     client.DeliveryMethod = SmtpDeliveryMethod.Network; 
     client.Credentials = new NetworkCredential("[email protected]", "myp"); 
     client.EnableSsl = true; 
     client.Timeout = 20000; 
     try 
     { 
      client.Send(msg); 
      return "Mail has been successfully sent!"; 
     } 
     catch (Exception ex) 
     { 
      return "Fail Has error" + ex.Message; 
     } 
     finally 
     { 
      msg.Dispose(); 
     } 
}

顯示消息：