無法連接到SMTP主機：smtp.gmail.com，端口：587;嵌套異常是：java.net.ConnectException：連接超時：連接

Question

這是應用程序的代碼。我一直在嘗試使用eclipse IDE來運行它。我還添加了所有必需的java郵件jar文件，即 dsn.jar,imap.jar,mailapi.jar,pop3.jar,smtp.jar,mail.jar。 但它給出了以下錯誤Could not connect to SMTP host: smtp.gmail.com, port: 587。

沒有防火牆阻止訪問，因爲在ping smtp.gmail.com時收到回覆。 我甚至嘗試了這種方式：

• 首先登錄在設備上的瀏覽器的Gmail帳戶，您要設置/使用客戶端
• 轉到這裏，並啓用「不太安全」的應用程序訪問：https://www.google.com/settings/security/lesssecureapps
• 然後轉到此處：https://accounts.google.com/b/0/DisplayUnlockCaptcha然後單擊繼續。
• 然後立即回到您的客戶端並重試。

javax.mail.MessagingException的：無法連接到SMTP主機： smtp.gmail.com，端口：587; 嵌套的異常是： java.net.ConnectException：連接超時：連接 at com.sun.mail.smtp.SMTPTransport.openServer（SMTPTransport.java:1972） at com.sun.mail.smtp.SMTPTransport.protocolConnect （SMTPTransport.java:642） at javax.mail.Service.connect（Service.java:317） at javax.mail.Service.connect（Service.java:176） at javax.mail.Service.connect（Service的.java：125） 在javax.mail.Transport.send0（Transport.java:194） 在javax.mail.Transport.send（Transport.java:124） 在PlainTextEmailSender.sendPlainTextEmail（PlainTextEmailSender.java:50） 在PlainTextEmailSender.main（PlainTextEmailSender.java:73） 導致：java.net.ConnectException：連接超時：連接 在java.net.DualStackPlainSocketImpl.connect0（本地方法） 在java.net.DualStackPlainSocketImpl.socketConnect（未知源） 在java.net.AbstractPlainSocketImpl.doConnect （未知來源） 在java.net.AbstractPlainSocketImpl.connectToAddress（未知來源） 在java.net.AbstractPlainSocketImpl.connect（未知來源） 在java.net.PlainSocketImpl.connect（未知來源） 在java.net.SocksSocketImpl （Unknown Source） at java.net.Socket.connect（Unknown Source） at java.net.Socket.connect（Unknown Source） at com.sun.mail.util.SocketFetcher.createSocket（SocketFetcher.java： 319） 在com.sun.mail.util.SocketFetcher.getSocket（SocketFetcher.java:233） 在com.sun.mail.smtp.SMTPTransport.openServer（SMTPTransport.java:1938）

package net.codejava.mail; 

    import java.util.Date; 
    import java.util.Properties; 

    import javax.mail.Authenticator; 
    import javax.mail.Message; 
    import javax.mail.MessagingException; 
    import javax.mail.PasswordAuthentication; 
    import javax.mail.Session; 
    import javax.mail.Transport; 
    import javax.mail.internet.AddressException; 
    import javax.mail.internet.InternetAddress; 
    import javax.mail.internet.MimeMessage; 

    public class PlainTextEmailSender { 

     public void sendPlainTextEmail(String host, String port, 
       final String userName, final String password, String toAddress, 
       String subject, String message) throws AddressException, 
       MessagingException { 

      // sets SMTP server properties 
      Properties properties = new Properties(); 
      properties.put("mail.smtp.host", host); 
      properties.put("mail.smtp.port", port); 
      properties.put("mail.smtp.auth", "true"); 
      properties.put("mail.smtp.starttls.enable", "true"); 

      // creates a new session with an authenticator 
      Authenticator auth = new Authenticator() { 
       public PasswordAuthentication getPasswordAuthentication() { 
        return new PasswordAuthentication(userName, password); 
       } 
      }; 

      Session session = Session.getInstance(properties, auth); 

      // creates a new e-mail message 
      Message msg = new MimeMessage(session); 

      msg.setFrom(new InternetAddress(userName)); 
      InternetAddress[] toAddresses = { new InternetAddress(toAddress) }; 
      msg.setRecipients(Message.RecipientType.TO, toAddresses); 
      msg.setSubject(subject); 
      msg.setSentDate(new Date()); 
      // set plain text message 
      msg.setText(message); 

      // sends the e-mail 
      Transport.send(msg); 

     } 

     /** 
     * Test the send e-mail method 
     * 
     */ 
     public static void main(String[] args) { 
      // SMTP server information 
      String host = "smtp.gmail.com"; 
      String port = "587"; 
      String mailFrom = "user_name"; 
      String password = "password"; 

      // outgoing message information 
      String mailTo = "email_address"; 
      String subject = "Hello my friend"; 
      String message = "Hi guy, Hope you are doing well. Duke."; 

      PlainTextEmailSender mailer = new PlainTextEmailSender(); 

      try { 
       mailer.sendPlainTextEmail(host, port, mailFrom, password, mailTo, 
         subject, message); 
       System.out.println("Email sent."); 
      } catch (Exception ex) { 
       System.out.println("Failed to sent email."); 
       ex.printStackTrace(); 
      } 
     } 
    } 

Answer 1

作爲我說過，你的代碼沒有問題。如果有什麼事情，只是做了一些測試，嘗試刪除驗證部分，看看是否能工作：

public void sendPlainTextEmail(String host, String port, 
      final String userName, final String password, String toAddress, 
      String subject, String message) throws AddressException, 
      MessagingException { 

     // sets SMTP server properties 
     Properties properties = new Properties(); 
     properties.put("mail.smtp.host", host); 
     properties.put("mail.smtp.port", port); 
     properties.put("mail.smtp.auth", "true"); 
     properties.put("mail.smtp.starttls.enable", "true"); 
// *** BEGIN CHANGE 
     properties.put("mail.smtp.user", userName); 

     // creates a new session, no Authenticator (will connect() later) 
     Session session = Session.getDefaultInstance(properties); 
// *** END CHANGE 

     // creates a new e-mail message 
     Message msg = new MimeMessage(session); 

     msg.setFrom(new InternetAddress(userName)); 
     InternetAddress[] toAddresses = { new InternetAddress(toAddress) }; 
     msg.setRecipients(Message.RecipientType.TO, toAddresses); 
     msg.setSubject(subject); 
     msg.setSentDate(new Date()); 
     // set plain text message 
     msg.setText(message); 

// *** BEGIN CHANGE 
     // sends the e-mail 
     Transport t = session.getTransport("smtp"); 
     t.connect(userName, password); 
     t.sendMessage(msg, msg.getAllRecipients()); 
     t.close(); 
// *** END CHANGE 

    } 

這就是我每天都使用從我的應用程序發送幾十封電子郵件的代碼，它是100 ％保證工作 - 當然，只要smtp.gmail.com:587是可到達的。

Answer 2

電子郵件通過成功的Gmail使用JDK 7與設置下面Gmail。

轉到Gmail設置>帳戶和導入>其他谷歌帳戶設置>下登錄在&安全

1. 兩步驟驗證：關
2. 允許不夠安全的應用：ON
3. 應用密碼：1個密碼（16個字符長），以後與此替換當前密碼。

使用以下Maven的依賴關係：

spring-core:4.2.2 
spring-beans:4.2.2 
spring-context:4.2.2 
spring-context-support:4.2.2 
spring-expression:4.2.2 
commons-logging:1.2 

<dependency> 
    <groupId>javax.mail</groupId> 
    <artifactId>mail</artifactId> 
    <version>1.4.7</version> 
</dependency> 

和我的源代碼是：

import org.springframework.mail.javamail.JavaMailSenderImpl; 
import org.springframework.mail.javamail.MimeMessageHelper; 

import javax.mail.MessagingException; 
import javax.mail.internet.MimeMessage; 
import javax.swing.JOptionPane; 
import java.util.List; 
import java.util.Properties; 

public class Email { 

    public final void prepareAndSendEmail(String htmlMessage, String toMailId) { 

     final OneMethod oneMethod = new OneMethod(); 
     final List<char[]> resourceList = oneMethod.getValidatorResource(); 

     //Spring Framework JavaMailSenderImplementation  
     JavaMailSenderImpl mailSender = new JavaMailSenderImpl(); 
     mailSender.setHost("smtp.gmail.com"); 
     mailSender.setPort(465); 

     //setting username and password 
     mailSender.setUsername(String.valueOf(resourceList.get(0))); 
     mailSender.setPassword(String.valueOf(resourceList.get(1))); 

     //setting Spring JavaMailSenderImpl Properties 
     Properties mailProp = mailSender.getJavaMailProperties(); 
     mailProp.put("mail.transport.protocol", "smtp"); 
     mailProp.put("mail.smtp.auth", "true"); 
     mailProp.put("mail.smtp.starttls.enable", "true"); 
     mailProp.put("mail.smtp.starttls.required", "true"); 
     mailProp.put("mail.debug", "true"); 
     mailProp.put("mail.smtp.ssl.enable", "true"); 
     mailProp.put("mail.smtp.user", String.valueOf(resourceList.get(0))); 

     //preparing Multimedia Message and sending 
     MimeMessage mimeMessage = mailSender.createMimeMessage(); 
     try { 
      MimeMessageHelper helper = new MimeMessageHelper(mimeMessage, true); 
      helper.setTo(toMailId); 
      helper.setSubject("I achieved the Email with Java 7 and Spring"); 
      helper.setText(htmlMessage, true);//setting the html page and passing argument true for 'text/html' 

      //Checking the internet connection and therefore sending the email 
      if(OneMethod.isNetConnAvailable()) 
       mailSender.send(mimeMessage); 
      else 
       JOptionPane.showMessageDialog(null, "No Internet Connection Found..."); 
     } catch (MessagingException e) { 
      e.printStackTrace(); 
     } 

    } 

} 

希望這會幫助別人。