I checked and it was set to No email notifications. However, I went in again and clicked on "Save" without changing anything and I haven't received any further notifications of responses to subscribed to threads. So, maybe that's all I needed to do, but it was strange since the only thing I did was change the email address. I am continuing to receive notifications of PMs, however, that's not an issue since there are few of them, relatively.

I changed from hotmail to me.com.