Trying to send email via Service Account getting com.google.api.client.auth.oauth2.TokenResponseException: 401 Unauthorized

Question

I have a Google Apps account. I'm trying to simply send an email on behalf of a user using a Service Account.

I've scoured the internet and nothing is working and i'm nearly at a loss.

I've followed the Java guides and i still keep getting com.google.api.client.auth.oauth2.TokenResponseException: 401 Unauthorized

Why does this code snippet give me 401 Unauthorized?

JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();

            GoogleCredential credential = new GoogleCredential.Builder()
                    .setTransport(httpTransport)
                    .setJsonFactory(JSON_FACTORY)
                    .setServiceAccountId("[email protected]")
                    .setServiceAccountPrivateKeyFromP12File(new File("path/to/file/myProject.p12"))
                    .setServiceAccountScopes(GmailScopes.all())
                    .setServiceAccountUser("[email protected]")
                    .build();

Gmail gmailService = new Gmail.Builder(httpTransport, JSON_FACTORY, credential)
                    .setApplicationName("My App") // DOES IT MATTER WHAT THIS IS SET TO?
                    .build();

MimeMessage mimeMessage = createEmail("[email protected]", "[email protected]", "Testing", "hey");
sendMessage(gmailService, "me", mimeMessage);

These methods are basically copy/paste from Googles documentation:

/**
     * Create a MimeMessage using the parameters provided.
     *
     * @param to email address of the receiver
     * @param from email address of the sender, the mailbox account
     * @param subject subject of the email
     * @param bodyText body text of the email
     * @return the MimeMessage to be used to send email
     * @throws MessagingException
     */
    public static MimeMessage createEmail(String to,
                                          String from,
                                          String subject,
                                          String bodyText)
            throws MessagingException {
        Properties props = new Properties();
        Session session = Session.getDefaultInstance(props, null);

        MimeMessage email = new MimeMessage(session);

        email.setFrom(new InternetAddress(from));
        email.addRecipient(javax.mail.Message.RecipientType.TO,
                new InternetAddress(to));
        email.setSubject(subject);
        email.setText(bodyText);
        return email;
    }

    /**
       * Send an email from the user's mailbox to its recipient.
       *
       * @param service Authorized Gmail API instance.
       * @param userId User's email address. The special value "me"
       * can be used to indicate the authenticated user.
       * @param email Email to be sent.
       * @throws MessagingException
       * @throws IOException
       */
      public static void sendMessage(Gmail service, String userId, MimeMessage email)
          throws MessagingException, IOException {
        Message message = createMessageWithEmail(email);
        System.out.println("userId = " + userId);
        message = service.users().messages().send(userId, message).execute();

        System.out.println("Message id: " + message.getId());
        System.out.println(message.toPrettyString());
      }

      /**
       * Create a Message from an email
       *
       * @param email Email to be set to raw of message
       * @return Message containing base64url encoded email.
       * @throws IOException
       * @throws MessagingException
       */
      public static Message createMessageWithEmail(MimeMessage email)
          throws MessagingException, IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        email.writeTo(baos);
        String encodedEmail = Base64.encodeBase64URLSafeString(baos.toByteArray());
        Message message = new Message();
        message.setRaw(encodedEmail);
        return message;
      }

I just get this stacktrace:

com.google.api.client.auth.oauth2.TokenResponseException: 401 Unauthorized
    at com.google.api.client.auth.oauth2.TokenResponseException.from(TokenResponseException.java:105)
    at com.google.api.client.auth.oauth2.TokenRequest.executeUnparsed(TokenRequest.java:287)
    at com.google.api.client.auth.oauth2.TokenRequest.execute(TokenRequest.java:307)
    at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.executeRefreshToken(GoogleCredential.java:384)
    at com.google.api.client.auth.oauth2.Credential.refreshToken(Credential.java:489)
    at com.google.api.client.auth.oauth2.Credential.intercept(Credential.java:217)
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:859)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:419)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:352)
    at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:469)
    at com.my.services.NotificationServiceTest.testGmailCredential(NotificationServiceTest.java:96)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
    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)

I have my service account created and set to domain wide delegation and here's a screenshot of my Manage API client access scopes:

What am i missing that I keep get 401 Unauthorized?

Answer 1

After a lengthy, yet helpful phone call with Google Support, we finally tracked down that if I changed GmailScopes.all() to the explicit scopes below then it worked.

Collection<String> SCOPES 
    = Collections.unmodifiableCollection(
            Arrays.asList(
                    new String[]{
                            GmailScopes.GMAIL_COMPOSE,
                            GmailScopes.GMAIL_SEND
                    }));

The support guy wasn't 100% sure, but he thought that maybe since my user didn't have access to ALL the gmail scopes and I was specifying GmailScopes.all() that it was error'ing with 401 Unauthorized before even checking which scope I was trying to use.

Answer 2

look over here, seems you don't have the access token yet! add refeshToken to your code:

        GoogleCredential credential = new GoogleCredential.Builder()
            .setTransport(httpTransport)
            .setJsonFactory(JSON_FACTORY)
            .setServiceAccountId("[email protected]")
            .setServiceAccountPrivateKeyFromP12File(new File("path/to/file/myProject.p12"))
            .setServiceAccountScopes(GmailScopes.all())
            .setServiceAccountUser("[email protected]")
            .build();

        credential.refreshToken();