Select image and send it by mail // Share attachment in mail

Good morning. I'm trying to make an application that allows you to select an image (from the gallery or any place where there are images) and send it by mail. I was looking everywhere but I can not manage to send the image, sending only text is simple ... but with the image becomes complicated. I attach a code that I think is the most likely to walk. It is not my property, then I leave the link of the creator. link

MainActivity.java

public class MainActivity extends Activity implements OnClickListener {

EditText editTextEmail, editTextSubject, editTextMessage;
Button btnSend, btnAttachment;
String email, subject, message, attachmentFile;
Uri URI = null;
private static final int PICK_FROM_GALLERY = 101;
int columnIndex;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    editTextEmail = (EditText) findViewById(R.id.editTextTo);
    editTextSubject = (EditText) findViewById(R.id.editTextSubject);
    editTextMessage = (EditText) findViewById(R.id.editTextMessage);
    btnAttachment = (Button) findViewById(R.id.buttonAttachment);
    btnSend = (Button) findViewById(R.id.buttonSend);

    btnSend.setOnClickListener(this);
    btnAttachment.setOnClickListener(this);
}

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    if (requestCode == PICK_FROM_GALLERY && resultCode == RESULT_OK) {
        /**
         * Get Path
         */
        Uri selectedImage = data.getData();
        String[] filePathColumn = { MediaStore.Images.Media.DATA };

        Cursor cursor = getContentResolver().query(selectedImage,filePathColumn, null, null, null);
        cursor.moveToFirst();
        columnIndex = cursor.getColumnIndex(filePathColumn[0]);
        attachmentFile = cursor.getString(columnIndex);
        Log.e("Attachment Path:", attachmentFile);
        URI = Uri.parse("file://" + attachmentFile);
        cursor.close();
    }
}

@Override
public void onClick(View v) {

    if (v == btnAttachment) {
        openGallery();

    }
    if (v == btnSend) {
        try {
            email = editTextEmail.getText().toString();
            subject = editTextSubject.getText().toString();
            message = editTextMessage.getText().toString();

            final Intent emailIntent = new Intent(
                    android.content.Intent.ACTION_SEND);
            emailIntent.setType("plain/text");
            emailIntent.putExtra(android.content.Intent.EXTRA_EMAIL,
                    new String[] { email });
            emailIntent.putExtra(android.content.Intent.EXTRA_SUBJECT,
                    subject);
            if (URI != null) {
                emailIntent.putExtra(Intent.EXTRA_STREAM, URI);
            }
            emailIntent
                    .putExtra(android.content.Intent.EXTRA_TEXT, message);
            this.startActivity(Intent.createChooser(emailIntent,
                    "Sending email..."));

        } catch (Throwable t) {
            Toast.makeText(this,
                    "Request failed try again: " + t.toString(),
                    Toast.LENGTH_LONG).show();
        }
    }

}

public void openGallery() {
    Intent intent = new Intent();
    intent.setType("image/*");
    intent.setAction(Intent.ACTION_GET_CONTENT);
    intent.putExtra("return-data", true);
    startActivityForResult(
            Intent.createChooser(intent, "Complete action using"),
            PICK_FROM_GALLERY);

}
}

activity_main.xml

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_margin="5dp"
    android:padding="5dp" >

    <EditText
        android:id="@+id/editTextTo"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_margin="5dp"
        android:hint="Email Address!"
        android:inputType="textEmailAddress"
        android:singleLine="true" />

    <EditText
        android:id="@+id/editTextSubject"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/editTextTo"
        android:layout_margin="5dp"
        android:hint="Subject"
        android:singleLine="true" />

    <EditText
        android:id="@+id/editTextMessage"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:layout_below="@id/editTextSubject"
        android:layout_margin="5dp"
        android:gravity="top|left"
        android:hint="type message here!"
        android:inputType="textMultiLine" />

    <Button
        android:id="@+id/buttonSend"
        android:layout_width="80dp"
        android:layout_height="50dp"
        android:layout_below="@id/editTextMessage"
        android:layout_margin="5dp"
        android:text="Send" />

    <Button
        android:id="@+id/buttonAttachment"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:layout_alignParentRight="true"
        android:layout_alignParentTop="true"
        android:text="attachment" />
</RelativeLayout>

Manifest permissions

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

I think the error arises when you try to get the address of the file. I hope you can help me with this problem, or guide me in the creation of another code. What I need is for the user to choose the image that he wants to send and this was sent by email.