Aha! That's why it suddenly resumed working for me.
When I realized it had stopped, my first assumption (incorrect) was that my settings had been corrupted. I was poking around and checked that Daily Newsletter box. The subscription resumed, and I thought I had fixed a problem related to only my account.
It wasn't until the other post that I realized this was a global problem, not an individual one.
Janet, there are a lot of users that are not sophisticated enough to find this setting. Are you sure you don't want to set it for everyone administratively?