Yes, but you should ideally not rely on it, or at least set it below your actual cap. This is because certain emails, such as important account notifications/registration confirmations/password reset emails etc, are not sent to the mail queue.
You also should not send any newsletters or other kind of bulk email from your forum if you have to cap emails per hour, if your member base is sufficiently large. For instance; if you have 40,000 members and have to limit emails to 1,000 per hour, it will take 40 hours to clear the mail queue, not counting any other outgoing mails that will be appended at the end of the queue.