Is it possible to use MailDev with Java?

I have a MailDev instance installed on a remote Server.

I'm trying to understand if is it possibile to send email with Java (using the standard JavaMailSender) using this fake SMTP server.

The config needs only the URL and the port but, in my case, it doesn't work.

It returns always:
Mail server connection failed; nested exception is com.sun.mail.util.MailConnectException: Couldn't connect to host ...

The WebUI is running correctly and I can see the empty inbox on server.

Thanks.

It seems like you are experience connections issues. Although I cannot tell you what the cause there is, perhaps I can offer an alternative solution to test your emails?

Using Wiser, you can run an embedded SMTP server and query that inside your junit test. I've used this a lot in my open source project Simple Java Mail and created a Rule for this:

package testutil.testrules;

import org.jetbrains.annotations.NotNull;
import org.junit.rules.ExternalResource;
import org.subethamail.smtp.server.SMTPServer;
import org.subethamail.wiser.Wiser;
import org.subethamail.wiser.WiserMessage;

import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintStream;
import java.util.Iterator;
import java.util.List;

/**
 * SmtpServerRule - a TestRule wrapping a Wiser instance (a SMTP server in Java), started and stopped right before and after each test.
 * <br>
 * SmtpServerRule exposes the same methods as the {@link Wiser} instance by delegating the implementation to the instance. These methods, however, can not be
 * used outside a JUnit statement (otherwise an {@link IllegalStateException} is raised).
 * <br>
 * The {@link Wiser} instance can be directly retrieved but also only from inside a JUnit statement.
 */
public class SmtpServerRule extends ExternalResource {
	private final Wiser wiser = new Wiser();
	private final int port;

	public SmtpServerRule(@NotNull Integer port) {
		this.port = port;
	}

	@Override
	protected void before() {
		this.wiser.setPort(port);
		this.wiser.start();
	}

	@Override
	protected void after() {
		this.wiser.stop();
	}

	@NotNull
	public Wiser getWiser() {
		checkState("getWiser()");
		return this.wiser;
	}

	@NotNull
	public List<WiserMessage> getMessages() {
		checkState("getMessages()");
		return wiser.getMessages();
	}
	
	@NotNull
	public MimeMessage getOnlyMessage(String envelopeReceiver)
			throws MessagingException {
		checkState("getMessages()");
		List<WiserMessage> messages = getMessages();
		assertThat(messages).hasSize(1);
		Iterator<WiserMessage> iterator = messages.iterator();
		WiserMessage wiserMessage = iterator.next();
		assertThat(wiserMessage.getEnvelopeReceiver()).isEqualTo(envelopeReceiver);
		MimeMessage mimeMessage = wiserMessage.getMimeMessage();
		iterator.remove();
		return mimeMessage;
	}
	
	@NotNull
	public MimeMessageAndEnvelope getOnlyMessage()
			throws MessagingException {
		checkState("getMessages()");
		List<WiserMessage> messages = getMessages();
		assertThat(messages).hasSize(1);
		Iterator<WiserMessage> iterator = messages.iterator();
		WiserMessage wiserMessage = iterator.next();
		iterator.remove();
		return new MimeMessageAndEnvelope(wiserMessage.getMimeMessage(), wiserMessage.getEnvelopeSender());
	}
	
	@NotNull
	public MimeMessage getMessage(String envelopeReceiver)
			throws MessagingException {
		checkState("getMessages()");
		List<WiserMessage> messages = getMessages();
		Iterator<WiserMessage> iterator = messages.iterator();
		while (iterator.hasNext()) {
			WiserMessage wiserMessage = iterator.next();
			if (wiserMessage.getEnvelopeReceiver().equals(envelopeReceiver)) {
				MimeMessage mimeMessage = wiserMessage.getMimeMessage();
				iterator.remove();
				return mimeMessage;
			}
		}
		throw new AssertionError("message not found for recipient " + envelopeReceiver);
	}

	@NotNull
	public SMTPServer getServer() {
		checkState("getServer()");
		return wiser.getServer();
	}

	public boolean accept(String from, String recipient) {
		checkState("accept(String, String)");
		return wiser.accept(from, recipient);
	}

	public void deliver(String from, String recipient, InputStream data)
			throws IOException {
		checkState("deliver(String, String, InputStream)");
		wiser.deliver(from, recipient, data);
	}

	public void dumpMessages(PrintStream out)
			throws MessagingException {
		checkState("dumpMessages(PrintStream)");
		wiser.dumpMessages(out);
	}

	private void checkState(String method) {
		if (this.wiser == null) {
			throw new IllegalStateException(format("%s must not be called outside of a JUnit statement", method));
		}
	}
}

Then I use it like this:

public class MailerLiveTest {
	private static final Integer SERVER_PORT = 251;

	@Rule
	public final SmtpServerRule smtpServerRule = new SmtpServerRule(SERVER_PORT);

	@Before
	public void setup() {
		mailer = MailerBuilder.withSMTPServer("localhost", SERVER_PORT).buildMailer();
	}
	
	@Test
	public void createMailSession_EmptySubjectAndBody() {
		// send mail using mailer, which goes to localhost:251

		MimeMessageAndEnvelope receivedMimeMessage = smtpServerRule.getOnlyMessage();
		Email receivedEmail = EmailConverter.mimeMessageToEmail(receivedMimeMessage.getMimeMessage());

		// perform assertions on Email object...
	}
}

Check if mail.smtp.auth and mail.smtp.starttls.enable are set to false. In my case it worked (I also set localhost as host and 1025 as port).