@Test
public void sendSimpleEmailInvalidAndValidAddressTest() throws Exception {

    CompletableFuture<Set<String>> cf = es.sendSimpleEmail(SUBJECT_LINE, TEXT_MESSAGE, "badAddress", TO_EMAIL_ADDRESS);
    Set<String> failedEmails = cf.get();
    assertEquals(1, failedEmails.size());
    assertEquals("badAddress", failedEmails.iterator().next());
}