[Java for Android App Development] vijai2011:
Here is the code as I promised.

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 = true; // 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.
// Lists the Available mime types for the mail
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);
}

public Mail(String user, String pass) {
this();

_user = user;
_pass = pass;
}

public boolean send() throws Exception {
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());

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 Exception {
BodyPart messageBodyPart = new MimeBodyPart();
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);

_multipart.addBodyPart(messageBodyPart);
}

[MENTION=439709]override[/MENTION]
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");
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.transport.protocol", "smtp");

return props;
}

public String getBody() {
return _body;
}

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

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

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

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

}

And here is the async task to do the actual work:

class MyTask extends AsyncTask<Void, Void, Void> {

[MENTION=439709]override[/MENTION]
protected void onPreExecute() {
prog = new ProgressDialog(context);
prog.setCancelable(false);
prog.setTitle("Sending...");
prog.setMessage("Please wait!Your mail is being sent...");
prog.setIndeterminate(false);
// prog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
prog.show();
}

protected Void doInBackground(Void... params) {

//get user and pass from edittext

Mail m = new Mail(user, pass);

String[] toArr = { "id1@domain.tld", id2@domain.tld};
m.setTo("To address here");
m.setFrom("your name");
m.setSubject("your sub");
m.setBody("Email body");

File file = new File("/data/log/dumpstate_app_error.txt.gz");
boolean exists = file.exists();
if (exists) {
try {
m.addAttachment("/data/log/dumpstate_app_error.txt.gz");
// Toast.makeText(Report.this,
// "There is no problem in sending mail!!!!!",
// Toast.LENGTH_LONG).show();
// finish();

if (m.send()) {
Toast.makeText(Report.this,
"Email was not sent successfully.",
Toast.LENGTH_LONG).show();
} else {
Toast.makeText(Report.this, "Email was not sent.",
Toast.LENGTH_LONG).show();
}
} catch (Exception e) {
// Toast.makeText(MailApp.this,
// "There was a problem sending the email.",
// Toast.LENGTH_LONG).show();
Log.e("mail", "Could not send email", e);
}
}

return null;
}

[MENTION=439709]override[/MENTION]
protected void onPostExecute(Void aVoid) {

super.onPostExecute(aVoid);
prog.dismiss();

Toast.makeText(context,
user_name + " Your mail was sent.Thanks for your time.",
Toast.LENGTH_LONG).show();
finish();
}

}

Actually the mail class already is a open source and the libs to attach to the project are attached with this post.