Class for sending mail without using built-in applications in android [working]

Mail.java

import java.util.Date;
import java.util.Properties;
import javax.activation.CommandMap;
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.activation.MailcapCommandMap;
import javax.mail.BodyPart;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;

// IMPORTANT: Use AsyncTask for sending mail !!
public class Mail extends javax.mail.Authenticator {
    private String _user;
    private String _pass;
    private String[] _to;
    private String _from;
    private String _port;
    private String _sport;
    private String _host;
    private String _subject;
    private String _body;
    private boolean _auth;
    private boolean _debuggable;
    private Multipart _multipart;

    public Mail() {
        _host = "smtp.gmail.com"; // default smtp server
        _port = "465"; // default smtp port
        _sport = "465"; // default socketfactory port
        _user = ""; // username
        _pass = ""; // password
        _from = ""; // email sent from
        _subject = ""; // email subject
        _body = ""; // email body
        _debuggable = false; // debug mode on or off - default off
        _auth = true; // smtp authentication - default on
        _multipart = new MimeMultipart();
        // There is something wrong with MailCap, javamail can not find a handler for the multipart/mixed part, so this bit needs to be added.
        MailcapCommandMap mc = (MailcapCommandMap) CommandMap.getDefaultCommandMap();
        mc.addMailcap("text/html;; x-java-content-handler=com.sun.mail.handlers.text_html");
        mc.addMailcap("text/xml;; x-java-content-handler=com.sun.mail.handlers.text_xml");
        mc.addMailcap("text/plain;; x-java-content-handler=com.sun.mail.handlers.text_plain");
        mc.addMailcap("multipart/*;; x-java-content-handler=com.sun.mail.handlers.multipart_mixed");
        mc.addMailcap("message/rfc822;; x-java-content-handler=com.sun.mail.handlers.message_rfc822");
        CommandMap.setDefaultCommandMap(mc);
    }

    /**
     * @param user
     *              Gmail account username (in other words, your mail address)
     * @param password
     *              Gmail account password
     */
    public Mail(String user, String password) {
        this();
        _user = user;
        _pass = password;
    }

    /**
     * @return
     *          true --- if sending operation successfully
     * @throws
     *          MessagingException
     */
    public boolean send() throws MessagingException {
        Properties props = _setProperties();

        if (!_user.equals("") && !_pass.equals("") && _to.length > 0 && !_from.equals("") && !_subject.equals("") && !_body.equals(""))
        {
            Session session = Session.getInstance(props, this);
            MimeMessage msg = new MimeMessage(session);
            msg.setFrom(new InternetAddress(_from));
            InternetAddress[] addressTo = new InternetAddress[_to.length];
            for (int i = 0; i < _to.length; i++)
                addressTo[i] = new InternetAddress(_to[i]);
            msg.setRecipients(MimeMessage.RecipientType.TO, addressTo);
            msg.setSubject(_subject);
            msg.setSentDate(new Date());
            // setup message body
            BodyPart messageBodyPart = new MimeBodyPart();
            messageBodyPart.setText(_body);
            _multipart.addBodyPart(messageBodyPart);
            msg.setContent(_multipart);
            Transport.send(msg);
            return true;
        }
        else
            return false;
    }

    public void addAttachment(String filename) throws MessagingException {
        BodyPart messageBodyPart = new MimeBodyPart();
        DataSource source = new FileDataSource(filename);
        messageBodyPart.setDataHandler(new DataHandler(source));
        messageBodyPart.setFileName(filename);
        _multipart.addBodyPart(messageBodyPart);
    }

    public void setTo(String[] toArr) {
        this._to = toArr;
    }

    public void setFrom(String string) {
        this._from = string;
    }

    public void setSubject(String string) {
        this._subject = string;
    }

    public void setBody(String _body) {
        this._body = _body;
    }

    // more of the getters and setters...

    @Override
    public PasswordAuthentication getPasswordAuthentication() {
        return new PasswordAuthentication(_user, _pass);
    }

    private Properties _setProperties() {
        Properties props = new Properties();
        props.put("mail.smtp.host", _host);
        if(_debuggable)
            props.put("mail.debug", "true");
        if(_auth)
            props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.port", _port);
        props.put("mail.smtp.socketFactory.port", _sport);
        props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");
        props.put("mail.smtp.socketFactory.fallback", "false");
        return props;
    }
}