Java Mail Issue with Session.getInstance

Question

I am receiving the following exception when trying to use java mail;

java.lang.NoClassDefFoundError: com/sun/mail/util/MailLogger
    at javax.mail.Session.initLogger(Session.java:226)
    at javax.mail.Session.<init>(Session.java:210)
    at javax.mail.Session.getInstance(Session.java:247)
    at com.secondstory.mailsender.MailSender.createSmtpSession(MailSender.java:67)
    at com.secondstory.mailsender.MailSender.sendSimpleMessage(MailSender.java:38)
    at com.secondstory.mailsender.MailSender.generateLostPasswordEmail(MailSender.java:79)
    at com.secondstory.mailsender.MailSenderTest.shouldReturnTrueWithCredentialsSet(MailSenderTest.java:49)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:70)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:50)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: java.lang.ClassNotFoundException: com.sun.mail.util.MailLogger
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    ... 30 more

After searching stack overflow extensively (maybe not extensively enough - lets see!) I have found that we need two jars inside our maven pom for this too work. The two dependancies I have are as follows;

<dependency>
    <groupId>javax.mail</groupId>
    <artifactId>javax.mail-api</artifactId>
    <version>1.5.2</version>
    <scope>runtime</scope>
</dependency>
<dependency>
    <groupId>javax.activation</groupId>
    <artifactId>activation</artifactId>
    <version>1.1.1</version>
</dependency> 

Something has changed but I am not entirely sure what it is - as this worked previously. The code i have written where this element fails is as follows;

private static Session createSmtpSession() {
    final Properties props = new Properties();
    props.setProperty("mail.host", "host");
    props.setProperty("mail.smtp.auth", "true");
    props.setProperty("mail.smtp.starttls.enable", "true");
    props.setProperty("mail.transport.protocol", "smtp");
    //props.setProperty("mail.debug", "true");

    return Session.getInstance(props, new javax.mail.Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(
                            "username", "password");
                }
            });
}

Am I missing some config or should this work with the current setup that I have?

Thanks

Answer 1

Try adding this into Maven POM:

<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.5.2</version>
</dependency>

Answer 2

The problem is that you are trying to use javax.mail-api.jar. That is the wrong library. JavaMail is a Java EE specification, the interfaces of that specification are published in that javax.mail-api-1.6.1.jar, which only works when compiling. It doesn't provide an implementation of the specification, so it doesn't work at runtime.

You need to use an implementation of the JavaMail specification at runtime. You can find the reference implementation on https://javaee.github.io/javamail/ (but there are others, for example Java EE application servers usually include one).

For javax.mail-api.jar, https://javaee.github.io/javamail/ says:

The JavaMail API definitions only, suitable for compiling against; use only with a Maven “provided” dependency scope

Specifically in your case you need either javax.mail.jar or mailapi.jar + the jars of the specific protocols you want to use. For example mailapi.jar + smtp.jar if you only need smtp(s) support.

With Maven, you can use

<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.1</version>
</dependency>