Feed updated but no emails being sent to subscribers

When I update my blog, it does not automatically send out emails to Feedburner Email Subscribers. It worked previously, though within the past few weeks, it doesn't seem to be emailing. The feed is working properly, and all of the subscribers are still Active. I haven't changed any settings within my account recently.

I looked in the Feedburner Help and the Feedburner Google Group -- many others seem to be having this problem, though I couldn't find a solution.