That works:
final Intent ei = new Intent(Intent.ACTION_SEND_MULTIPLE);
ei.setType("plain/text");
ei.putExtra(Intent.EXTRA_EMAIL, new String[] {"[email protected]"});
ei.putExtra(Intent.EXTRA_SUBJECT, "That one works");
then add files’ uris:
ArrayList<Uri> uris = new ArrayList<Uri>();
ei.putParcelableArrayListExtra(Intent.EXTRA_STREAM, uris);
startActivityForResult(Intent.createChooser(ei, "Sending multiple attachment"), 12345);
Hope that helps.