javax.mail.MessagingException：无法连接到 SMTP 主机：本地主机，端口：25

Question

I am getting issue while sending email.

javax.mail.SendFailedException: Sending failed;
  nested exception is: 
    javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;
  nested exception is: 
    java.net.ConnectException: Connection refused: connect
    at javax.mail.Transport.send0(Transport.java:219)
    at javax.mail.Transport.send(Transport.java:81)
    at org.apache.jsp.online_005fScheme_005fSend_005fMail_jsp.sendMail(online_005fScheme_005fSend_005fMail_jsp.java:116)
    at org.apache.jsp.online_005fScheme_005fSend_005fMail_jsp._jspService(online_005fScheme_005fSend_005fMail_jsp.java:416)
    at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:98)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:369)
    at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:308)
    at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:259)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:879)
    at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
    at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
    at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
    at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
    at java.lang.Thread.run(Thread.java:619)

---

I use below code snipet.

Properties props = new Properties();
     props.put("mail.smtp.host", "10.101.3.229");

email send program is running on tomcat 5. Some times it is working fine and some times it results above exception. once it satart resulting above exception it results the same on every access. but as soon as i restart tomcat server it starts working fine again.

So i could not find what is reason. as sometimes same is working fine and sometimes results above exception.

Can anybody help me out this issue.

Answer 1

package sn;
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 SendEmail {
  public static void main(String[] args) {
    final String SSL_FACTORY = "javax.net.ssl.SSLSocketFactory";
 // Get a Properties object
    Properties props = System.getProperties();
    props.setProperty("mail.smtp.host", "smtp.gmail.com");
    props.setProperty("mail.smtp.socketFactory.class", SSL_FACTORY);
    props.setProperty("mail.smtp.socketFactory.fallback", "false");
    props.setProperty("mail.smtp.port", "465");
    props.setProperty("mail.smtp.socketFactory.port", "465");
    props.put("mail.smtp.auth", "true");
    props.put("mail.debug", "true");
    props.put("mail.store.protocol", "pop3");
    props.put("mail.transport.protocol", "smtp");
    final String username = "xxxx@gmail.com";//
    final String password = "0000000";
    try{
      Session session = Session.getDefaultInstance(props, 
                          new Authenticator(){
                             protected PasswordAuthentication getPasswordAuthentication() {
                                return new PasswordAuthentication(username, password);
                             }});

   // -- Create a new message --
      Message msg = new MimeMessage(session);

   // -- Set the FROM and TO fields --
      msg.setFrom(new InternetAddress("xxxx@gmail.com"));
      msg.setRecipients(Message.RecipientType.TO, 
                        InternetAddress.parse("user120@example.com",false));
      msg.setSubject("Hello");
      msg.setText("How are you");
      msg.setSentDate(new Date());
      Transport.send(msg);
      System.out.println("Message sent.");
    }catch (MessagingException e){ 
      System.out.println("Erreur d'envoi, cause: " + e);
    }
  }
}

Answer 2

It is very clear from your exception that it is trying to connect to localhost and not to 10.101.3.229

exception snippet : Could not connect to SMTP host: localhost, port: 25;

1.) Please check if there are any null check which is setting localhost as default value

2.) After restarting, if it is working fine, then it means that only at first-run, the proper value is been taken from Properties and from next run the value is set to default. So keep the property-object as a singleton one and use it all-over your project

Answer 3

This should not happen. Can you try doing this? Use the system properties and set the property as below:

Properties properties = System.getProperties();
// Setup mail server
properties.setProperty("mail.smtp.host", "10.101.3.229");

And if you have a port associated, then set this as well.

properties.setProperty("mail.smtp.port", "8080");

Answer 4

Try to set the property when starting JVM, for example, add -Djava.net.preferIPv4Stack=true .

You can't set it when code running, as the java.net just read it when jvm starting.

And about the root cause, this article give some hint: Why do I need java.net.preferIPv4Stack=true only on some windows 7 systems? .

Answer 5

I was also facing the same error. The reason for this is that there is no smtp server on your environment. For creating a fake smtp server I used this fake-smtp.jar file for creating a virtual server and listening to all the requests. If you are facing the same error, I recommend you to use this jar and run it after extracting and then try to run your application.

Download latest version of fake smtp

Answer 6

看看这个解决方案，确保你在你的谷歌帐户上打开了对安全性较低的应用程序的访问： javax.mail.MessagingException：无法连接到 SMTP 主机：本地主机，端口：25