Android ACTION_SEND intent no longer populating Subject or Body

I have code in my app which lets the user send an email to the developer. It prepopulated the To field, the Subject field, and the body field. Now when I run, it populates To but ignores the EXTRAs like Subject, Body, and Chooser text. I'm seeing this behavior on two test devices: one running Lollipop (Verizon Samsung Galaxy Note 4) and one running Jelly Bean 4.2.2 (Samsung Fascinate on CM10.1, although I don't know if this has bearing on the issue.

private void sendHelpEmail() {
    Intent email = new Intent(Intent.ACTION_SEND, Uri.parse("mailto:"));
    // prompts email clients only
    email.setType("message/rfc822");

    email.putExtra(Intent.EXTRA_EMAIL, new String[] {getString(R.string.about_email)});
    email.putExtra(Intent.EXTRA_SUBJECT, getString(R.string.login_help_subject));
    email.putExtra(Intent.EXTRA_TEXT, getString(R.string.login_help_body, classButton.text(), Txt_Student.getText().toString()));

    try {
        // the user can choose the email client
        startActivity(Intent.createChooser(email, getString(R.string.login_help_chooser)));
        } catch (android.content.ActivityNotFoundException ex) {
            Toast.makeText(mThis, R.string.login_help_error, Toast.LENGTH_LONG).show();
        }
}

Why would Subject and Body get ignored when the To email is populated?