Sending mail in android without intents using SMTP

config gradle as per below define get reference from Here

repositories { 
     jcenter()
     maven {
         url "https://maven.java.net/content/groups/public/"
     }
}

dependencies {
     compile 'com.sun.mail:android-mail:1.5.5'
     compile 'com.sun.mail:android-activation:1.5.5'
}

android {
   packagingOptions {
       pickFirst 'META-INF/LICENSE.txt' // picks the JavaMail license file
   }
}

Add this async task to send mail

 public class sendemail extends AsyncTask<String, Integer, Integer> {

    ProgressDialog progressDialog;
    private StringBuilder all_email;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        progressDialog = new ProgressDialog(GetuserActivity.this);
        progressDialog.setMessage("Uploading, please wait...");
        progressDialog.show();
        if (selecteduser_arr != null) {
            all_email = new StringBuilder();
            for (int i = 0; i < selecteduser_arr.size(); i++) {
                if (i == 0) {
                    all_email.append(selecteduser_arr.get(i));
                } else {
                    String temp = "," + selecteduser_arr.get(i);
                    all_email.append(temp);
                }
            }
        }
    }

    @Override
    protected Integer doInBackground(String... strings) {

        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 = Session.getDefaultInstance(props,
                new javax.mail.Authenticator() {
                    protected PasswordAuthentication getPasswordAuthentication() {
                        return new PasswordAuthentication("enterhereyouremail", "enterherepassword");
                    }
                });

        try {

            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("enterhereyouremail"));
            message.setRecipients(Message.RecipientType.TO,
                    InternetAddress.parse("[email protected],[email protected]"));
            message.setSubject("Testing Subject");
            message.setText("Dear Mail Crawler," +
                    "\n\n No spam to my email, please!");

            Transport.send(message);

            System.out.println("Done");

        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
        return 1;
    }

    @Override
    protected void onPostExecute(Integer integer) {
        super.onPostExecute(integer);
        progressDialog.dismiss();
    }
}

Put in your manifest file,

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

check if you have internet connection,

public boolean isOnline() {
    ConnectivityManager cm =
        (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo netInfo = cm.getActiveNetworkInfo();
    if (netInfo != null && netInfo.isConnectedOrConnecting()) {
        return true;
    }
    return false;
}

and finnaly use this code to send email

final String username = "[email protected]";
final String password = "password";

Properties props = new Properties();
props.put("mail.smtp.auth", "true");
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.host", "smtp.gmail.com");
props.put("mail.smtp.port", "587");

Session session = Session.getInstance(props,
  new javax.mail.Authenticator() {
    protected PasswordAuthentication getPasswordAuthentication() {
        return new PasswordAuthentication(username, password);
    }
  });
    try {
        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress("[email protected]"));
        message.setRecipients(Message.RecipientType.TO,
            InternetAddress.parse("[email protected]"));
        message.setSubject("Testing Subject");
        message.setText("Dear Mail Crawler,"
            + "\n\n No spam to my email, please!");

        MimeBodyPart messageBodyPart = new MimeBodyPart();

        Multipart multipart = new MimeMultipart();

        messageBodyPart = new MimeBodyPart();
        String file = "path of file to be attached";
        String fileName = "attachmentName"
        DataSource source = new FileDataSource(file);
        messageBodyPart.setDataHandler(new DataHandler(source));
        messageBodyPart.setFileName(fileName);
        multipart.addBodyPart(messageBodyPart);

        message.setContent(multipart);

        Transport.send(message);

        System.out.println("Done");

    } catch (MessagingException e) {
        throw new RuntimeException(e);
    }