Intent email = new Intent(Intent.ACTION_SEND);
email.putExtra(Intent.EXTRA_EMAIL, new String[]{ to});
email.putExtra(Intent.EXTRA_SUBJECT, subject);
email.putExtra(Intent.EXTRA_TEXT, message);
 
//need this to prompts email client only
email.setType("message/rfc822");

startActivity(Intent.createChooser(email, "Choose an Email client :"));

package com.example.sendemail;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity {
EditText editTextTo,editTextSubject,editTextMessage;
Button send;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

editTextTo=(EditText)findViewById(R.id.editText1);
editTextSubject=(EditText)findViewById(R.id.editText2);
editTextMessage=(EditText)findViewById(R.id.editText3);

send=(Button)findViewById(R.id.button1);

send.setOnClickListener(new OnClickListener(){

@Override
public void onClick(View arg0) {
 String to=editTextTo.getText().toString();
 String subject=editTextSubject.getText().toString();
 String message=editTextMessage.getText().toString();
 

 Intent email = new Intent(Intent.ACTION_SEND);
  email.putExtra(Intent.EXTRA_EMAIL, new String[]{ to});
  email.putExtra(Intent.EXTRA_SUBJECT, subject);
  email.putExtra(Intent.EXTRA_TEXT, message);
 
  //need this to prompts email client only
  email.setType("message/rfc822");
 
  startActivity(Intent.createChooser(email, "Choose an Email client :"));
 
}

});
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}

}