C＃smtpfailedrecipientsexception;如何退出功能，如果發生這種情況

Question

因此，這裏是我的代碼，用於從統一發送電子郵件使用C＃腳本：

public void SendMail() // Mail send function 
    { 
     string emailAddress; // variable to store user inputted email 
     emailAddress = emailInput.text; // variable becomes the email the user types in 
     mail.From = new MailAddress("hiddenfornow"); 
     mail.To.Add(emailAddress); 
     SmtpClient smtpServer = new SmtpClient("smtp.gmail.com"); 
     smtpServer.Port = 587; 
     mail.Subject = "Test Subject" + currentDate; 
     mail.IsBodyHtml = true; // allows for html 
     mail.Body = "Testing testing"; 
     smtpServer.Credentials = new System.Net.NetworkCredential("hiddenfornow", "hiddenfornow") as ICredentialsByHost; 
     smtpServer.EnableSsl = true; 
     SceneManager.LoadScene("TestScene"); // reloads the scene after user clicks button   
     ServicePointManager.ServerCertificateValidationCallback = 
     delegate (object s, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors) 
     { return true; }; 
     smtpServer.Send(mail); 
     Debug.Log("success"); 
} 

此代碼工作正常發送電子郵件。但是，如果我輸入了錯誤的電子郵件，我將收到「smtpfailedrecipientsexception」消息。

在此之後，即使輸入正確的電子郵件地址也不起作用。 smtpfailedrecipientsexception將繼續發生，除非您第一次輸入正確。

我想補充某種If語句，如這裏面我寫的僞代碼：

If smtpserver.send(mail)returns smtp error 
{ 
Exit this function 
} 
else 
{ 
success message 
} 

我只是不知道如何實現這一點。

謝謝你閱讀我的問題。

Answer 1

SmtpClient使用池來減少創建到服務器的新連接的開銷。 （參見：https://msdn.microsoft.com/en-us/library/system.net.mail.smtpclient(v=vs.110).aspx#Remarks）

我的假設是，SmtpFailedRecientsException是把連接成一個狀態不好，所以你需要強制連接客戶端配置關閉：

public void SendMail() // Mail send function 
    { 
     //your code... 

     SmtpClient smtpServer = new SmtpClient("smtp.gmail.com"); 

     try { 
      //.... your code continues..... 
      smtpServer.Send(mail); 
      Debug.Log("success"); 
     } catch (SmtpFailedRecipientsException) { //or, perhaps any Exception 
      smtpServer.Dispose(); 
      throw; //rethrow the exception, assuming you're handling it in the calling code 
     } 
} 

Answer 2

使用異常處理方法處理運行時異常：

 try 
     { 
      if (smtpserver.send(mail)) 
       return "successful"; 
     } 
     catch (SmtpFailedRecipientException ex) 
     { 
      // log your error 
      return ex.StatusCode; // return status code as you will know actual error code 
     } 
     finally 
     { 
      mail.Dispose(); // Dispose your mailmessage as it will clears any stream associated with your mail message such as attachment 

     } 

Available Status Codes

Answer 3

以供將來參考，在這裏是工作的代碼：

Try 
{ 
smtpServer.Send(mail); // Attempts to send the email 
Debug.Log("success"); 
} 
catch (SmtpFailedRecipientsException) // Catches send failure 
{ 
mail.Dispose(); // ends the SMTP connection 
SceneManager.LoadScene("SceneName"); //Reloads the scene to clear textboxes 
}