@Override
    public void execute(
            MailOptions mailOptions,
            final ThrowingRunnable<? extends Exception> command,
            final String descriptionFormat,
            final Object... descriptionArgs) {
        try {
            mailbox.put(
                    new Mail(
                            mailOptions,
                            command,
                            priority,
                            actionExecutor,
                            descriptionFormat,
                            descriptionArgs));
        } catch (MailboxClosedException mbex) {
            throw new RejectedExecutionException(mbex);
        }
    }
@Test
    void testOperations() throws Exception {
        AtomicBoolean wasExecuted = new AtomicBoolean(false);
        CompletableFuture.runAsync(
                        () -> mailboxExecutor.execute(() -> wasExecuted.set(true), ""),
                        otherThreadExecutor)
                .get();

        mailbox.take(DEFAULT_PRIORITY).run();
        assertThat(wasExecuted).isTrue();
    }