Great question, and there's nothing wrong with them! The 'in progress' is an indicator of those emails awaiting delivery. These emails are waiting on a response from the receiving server on whether it will accept them. Also, sometimes you might see a mailing in progress for up to 30 hours after you initially send. That's because we may not get through to all email addresses on the first attempt (they might have a full inbox or temporary server problem), so we'll try again a few more times. We do immediately attempt delivery, but we're not able to determine how quickly the receiving server accepts the message.