Question

I have an application that sends emails. But in my development environment, I don’t want the application to send email, rather it should only print the message in log file.

There are a fake javax.mail.Session implementation that I can do this?

Answer 1

For this problem I would use a custom javax.mail.Transport which is registered to the SMTP protocol.

First implement the CustomTransport class

import javax.mail.Transport;
import javax.mail.*;

public class CustomTransport extends Transport {

  public CustomTransport(Session smtpSession, URLName urlName) {
    super(smtpSession, urlName);
  }

  @Override
  public void sendMessage(Message message, Address[] addresses) throws MessagingException {
    // Take the message and write it somewhere
    // e.g.: a logger or an OutputStream message.writeTo(...);
  }

  @Override
  public void connect() throws MessagingException {}

  @Override
  public void connect(String host, int port, String username, String password) throws MessagingException {}

  @Override
  public void connect(String host, String username, String password) throws MessagingException {}

  @Override
  public void close() {}
}

Afterwards you can use that CustomTransport to create a javax.mail.Session which writes your mails to the defined location

public Session getMailSession(){
  Properties props = new Properties();
  props.put("mail.transport.protocol", "smtp");
  props.put("mail.smtp.provider.class", CustomTransport.class.getName());
  props.put("mail.smtp.provider.vendor", "foo");
  props.put("mail.smtp.provider.version", "0.0.0");

  return Session.getInstance(props);
}