How to send Email on Android using JavaMail API?

This example demonstrates how to send Email on Android using JavaMail API.
Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.
Step 2 − Add the following code to res/layout/activity_main.xml.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:app="http://schemas.android.com/apk/res-auto"
   xmlns:tools="http://schemas.android.com/tools"
   android:orientation="vertical"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:text="Recipient Email"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" />
   <EditText
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:id="@+id/editTextEmail" />
   <TextView
      android:text="Subject"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" />
   <EditText
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:id="@+id/editTextSubject" />
   <TextView
      android:text="Message"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content" />
   <EditText
      android:lines="4"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:id="@+id/editTextMessage" />
   <Button
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:id="@+id/buttonSend"
      android:text="Send"/>
</LinearLayout>
Step 3 − Add the following code to src/MainActivity.java
package com.app.sample;
import androidx.appcompat.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import java.util.Properties;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import android.os.Bundle;
public class MainActivity extends AppCompatActivity implements View.OnClickListener {
   private EditText editTextEmail;
   private EditText editTextSubject;
   private EditText editTextMessage;
   private Button buttonSend;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      editTextEmail = (EditText) findViewById(R.id.editTextEmail);
      editTextSubject = (EditText) findViewById(R.id.editTextSubject);
      editTextMessage = (EditText) findViewById(R.id.editTextMessage);
      buttonSend = (Button) findViewById(R.id.buttonSend);
      buttonSend.setOnClickListener(this);
   }
   private void sendEmail() {
      String email = editTextEmail.getText().toString().trim();
      String subject = editTextSubject.getText().toString().trim();
      String message = editTextMessage.getText().toString().trim();
      SendMail sm = new SendMail(this, email, subject, message);
      sm.execute();
   }
   @Override
   public void onClick(View v) {
      sendEmail();
   }
}
Step 4 − Add the following code to src/Config.java
package com.app.sample;
public class Config {
   public static final String EMAIL ="your-gmail-username";
   public static final String PASSWORD ="your-gmail-password";
}
Step 5 − Add the following code to src/SendMail.java
package com.app.sample;
import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.widget.Toast;
import java.util.Properties;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
public class SendMail extends AsyncTask{
   private Context context;
   private Session session;
   private String email;
   private String subject;
   private String message;
   private ProgressDialog progressDialog;
   public SendMail(Context context, String email, String subject, String message){
      this.context = context;
      this.email = email;
      this.subject = subject;
      this.message = message;
   }
   @Override
   protected void onPreExecute() {
      super.onPreExecute();
      progressDialog = ProgressDialog.show(context,"Sending message","Please wait...",false,false);
   }
   @Override
   protected void onPostExecute(Void aVoid) {
      super.onPostExecute(aVoid);
      progressDialog.dismiss();
      Toast.makeText(context,"Message Sent",Toast.LENGTH_LONG).show();
   }
   @Override
   protected Void doInBackground(Void... params) {
      Properties props = new Properties();
      props.put("mail.smtp.host", "smtp.gmail.com");
      props.put("mail.smtp.socketFactory.port", "465");
      props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
      props.put("mail.smtp.auth", "true");
      props.put("mail.smtp.port", "465");
      session = Session.getDefaultInstance(props, new javax.mail.Authenticator() {
         protected PasswordAuthentication getPasswordAuthentication() {
            return new PasswordAuthentication(Config.EMAIL, Config.PASSWORD);
         }
      });
      try {
         MimeMessage mm = new MimeMessage(session);
         mm.setFrom(new InternetAddress(Config.EMAIL));
         mm.addRecipient(Message.RecipientType.TO, new InternetAddress(email));
         mm.setSubject(subject);
         mm.setText(message);
         Transport.send(mm);
      }
      catch (MessagingException e) {
         e.printStackTrace();
      }
      return null;
   }
}
Step 6 − Add the following code to Manifests/AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.app.sample">
   <uses-permission android:name="android.permission.INTERNET"/>
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>
Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from the android studio, open one of your project's activity files and click Run  icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −
Click here to download the project code.