Hello friends, In this post, I will show how to send mail with GMail using OAuth2.0 in Android. This Project contains a lot of steps l...

Java Mail API using GMAIL OAuth API in Android Java Mail API using GMAIL OAuth API in Android

android, javamail api, gmail oauth 2, android mail api

Java Mail API using GMAIL OAuth API in Android

Java Mail API using GMAIL OAuth API in Android

Java Mail API using GMAIL OAuth API in Android
Hello friends, In this post, I will show how to send mail with GMail using OAuth2.0 in Android. This Project contains a lot of steps like Permission, Google Play Service check to do.
So, please download the project to perform GMail API completely.

First of All, we have to generate OAuth key in Google API Console. To Generate OAuth Key, use your SHA1 key and your app's Package Name as in your Manifest.Paste Following code in your Command Prompt to get SHA1 key in Windows
keytool -list -v -keystore "%USERPROFILE%\.android\debug.keystore" -alias androiddebugkey -storepass android -keypass android

Project Structure

Create a new Project in Android Studio with the required Specifications.


Don't forget to add the following permission in your manifest file.
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.GET_ACCOUNTS"/>
<!--Added for Accessing External Storage-->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
We have to add the following Jar Files into your Project as like Normal Java Mail API.
  1. mail.jar
  2. activation.jar
  3. additionnal.jar
Download Jars From Server


Open your app level build.gradle file add the following lines.
dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:23.3.0'
    compile 'com.android.support:design:23.3.0'
    compile 'com.google.android.gms:play-services-identity:8.4.0'
    compile('com.google.api-client:google-api-client-android:1.22.0') {
        exclude group: 'org.apache.httpcomponents'
    compile('com.google.apis:google-api-services-gmail:v1-rev44-1.22.0') {
        exclude group: 'org.apache.httpcomponents'
    compile files('libs/mail.jar')
    compile files('libs/activation.jar')
    compile files('libs/additionnal.jar')
Initialize the Google API Client as in the following.
GoogleAccountCredential mCredential;
String[] SCOPES = {
// Initialize credentials and service object.
mCredential = GoogleAccountCredential.usingOAuth2(
  getApplicationContext(), Arrays.asList(SCOPES))
  .setBackOff(new ExponentialBackOff());
Following line is used to start Account Pick in Android
// Start a dialog from which the user can choose an account
startActivityForResult(mCredential.newChooseAccountIntent(), Utils.REQUEST_ACCOUNT_PICKER);
Use the following code to generate and initialize all the processes regarding this project.
// Async Task for sending Mail using GMail OAuth
    private class MakeRequestTask extends AsyncTask {
        private com.google.api.services.gmail.Gmail mService = null;
        private Exception mLastError = null;
        private View view = sendFabButton;

        public MakeRequestTask(GoogleAccountCredential credential) {
            HttpTransport transport = AndroidHttp.newCompatibleTransport();
            JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
            mService = new com.google.api.services.gmail.Gmail.Builder(
                    transport, jsonFactory, credential)

        protected String doInBackground(Void... params) {
            try {
                return getDataFromApi();
            } catch (Exception e) {
                mLastError = e;
                return null;

        private String getDataFromApi() throws IOException {
            // getting Values for to Address, from Address, Subject and Body
            String user = "me";
            String to = Utils.getString(edtToAddress);
            String from = mCredential.getSelectedAccountName();
            String subject = Utils.getString(edtSubject);
            String body = Utils.getString(edtMessage);
            MimeMessage mimeMessage;
            String response = "";
            try {
                mimeMessage = createEmail(to, from, subject, body);
                response = sendMessage(mService, user, mimeMessage);
            } catch (MessagingException e) {
            return response;

        // Method to send email
        private String sendMessage(Gmail service,
                                   String userId,
                                   MimeMessage email)
                throws MessagingException, IOException {
            Message message = createMessageWithEmail(email);
            // GMail's official method to send email with oauth2.0
            message = service.users().messages().send(userId, message).execute();

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

        // Method to create email Params
        private 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);
            InternetAddress tAddress = new InternetAddress(to);
            InternetAddress fAddress = new InternetAddress(from);

            email.addRecipient(javax.mail.Message.RecipientType.TO, tAddress);

            // Create Multipart object and add MimeBodyPart objects to this object
            Multipart multipart = new MimeMultipart();

            // Changed for adding attachment and text
            // This line is used for sending only text messages through mail
            // email.setText(bodyText);

            BodyPart textBody = new MimeBodyPart();

            if (!(activity.fileName.equals(""))) {
                // Create new MimeBodyPart object and set DataHandler object to this object
                MimeBodyPart attachmentBody = new MimeBodyPart();
                String filename = activity.fileName; // change accordingly
                DataSource source = new FileDataSource(filename);
                attachmentBody.setDataHandler(new DataHandler(source));

            // Set the multipart object to the message object
            return email;

        private Message createMessageWithEmail(MimeMessage email)
                throws MessagingException, IOException {
            ByteArrayOutputStream bytes = new ByteArrayOutputStream();
            String encodedEmail = Base64.encodeBase64URLSafeString(bytes.toByteArray());
            Message message = new Message();
            return message;

        protected void onPreExecute() {

        protected void onPostExecute(String output) {
            if (output == null || output.length() == 0) {
                showMessage(view, "No results returned.");
            } else {
                showMessage(view, output);

        protected void onCancelled() {
            if (mLastError != null) {
                if (mLastError instanceof GooglePlayServicesAvailabilityIOException) {
                            ((GooglePlayServicesAvailabilityIOException) mLastError)
                } else if (mLastError instanceof UserRecoverableAuthIOException) {
                            ((UserRecoverableAuthIOException) mLastError).getIntent(),
                } else {
                    showMessage(view, "The following error occurred:\n" + mLastError.getMessage());
                    Log.v("Error", mLastError.getMessage());
            } else {
                showMessage(view, "Request Cancelled.");




You should add the following lines in proguard while releasing your APK
-keep class com.google.** 
Thanks to Kaba Droid42 for this.

Download Source Code

You can download the full source from the following Github link. If you Like this library, Please star it in Github.


  1. Hello! Thanks for sharing. That’s exactly what I need and it runs successfully. However, I still can't understand how you list all items that need to be agreed by users (The second Screenshot you post on the web). Could you let me know how to solve it or which part of codes in Main Activity I can figure out? Thank you very much.

  2. Actually, it is a built-in screen in the gmail-sdk and thanks for your comment

  3. Hello! I have a question about the code.
    It works very well only if I login with my account, which already generated OAuth Key.
    When I login with other accounts,
    "message = service.users().messages().send(userId, message).execute();"
    will throw UserRecoverableAuthException: NeedPermission
    How can I do to fix this problem?
    Thank you very much!

  4. I get an error: The following error occured: 403 Forbidden...
    How can I fix this?

    1. Are you enabled the Gmail API in your Google API Console ?

    2. If not enable it and try again.

  5. Hello...
    I followed your tutorial (compliments for this, very useful) I don't have problem if i use the SHA1 from my debugkeystore but, when i sign my apk for release and I put the SHA1 fingerprint in my API Manager Console, my app does not send email. No error on console, no error from my app it just stops sending email.

    Thank you for any help

    1. Ok, after a series of tests the problem is... ProGuard. If the value minifyEnabled in the build.gradle is true the email sender doesn't work, if in false all work.
      Any idea why?

    2. in the proguard-rules.pro use
      -keep class com.google.** {*;}
      -keep class com.google.**
      and all work! :)

    3. I have download your project and build it in android studio after successfully run when I send mail It just crushes.

    4. Will you explain it clearly bro ? Please

    5. Thanks for you reply. I have solved my problem :)

  6. Hi, your code works excellent and it helped me alot.... but can you please tell me about image sharing using this code ?... if so, i would help me alot mate :)

    1. Dear Geary,

      I have updated the post with sending mail with attachment.

      Thanks for your support and Keep on visiting Androidmads

  7. Thanks a lot! You made a new blog entry to answer my question; I really appreciate your time and effort.
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  8. I don't have REQUEST_ACCOUNT_PICKER in my Utils class in my android studio ..

  9. Hi Mushtaq,
    Thanks for the piece of information and codes.
    Is this implementation still working?
    I checked, the app looks working, but to enable api using OAuth/gmail has many restriction now, and needs verification, which I heard takes infinite time.
    Please guide to resolve this, or suggest any alternatives.

  10. Hi, Dear,
    Thanks for the code. I want to get the last gmail message from the user. Can you elaborate the codes please?

  11. Very useful information on Android App development. Using Xamarin for developing Android Mobile Apps would sure help businesses at a great level.
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  12. The tips you provided here are very valuable. It absolutely was such an exciting surprise to get that waiting for me immediately i woke up this very day. They are often to the point and straightforward to understand. Warm regards for the clever ideas you have shared above. aprende java


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