Try below code.
Intent emailIntent = new Intent(android.content.Intent.ACTION_SEND);
emailIntent.setType("png/image");
emailIntent.putExtra(android.content.Intent.EXTRA_EMAIL, new String[] {
"mail--id" });
emailIntent.putExtra(android.content.Intent.EXTRA_SUBJECT, subject);
emailIntent.putExtra(android.content.Intent.EXTRA_TEXT, message);
Uri uri = Uri.fromFile(new File(Environment
.getExternalStorageDirectory(), "/saved_images/MyImage.png"));
emailIntent.putExtra(Intent.EXTRA_STREAM, uri);
emailIntent.setType("text/plain");
startActivity(emailIntent);
and don't forget to add this below permission in manifest file.
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_INTERNAL_STORAGE" />