My friend is still MIA

Betty is still MIA. I email her at least once a week from work. Sometimes we chit-chat all day long via email. It's really fun talking to her. I emailed her yesterday and today and I haven't heard back from her. That's unusual even though she can't talk a lot every day, she does usally give me a short answer. Especially since it was a school related question. I'll email her again tomorrow.