We stopped getting our jotforms today at around 11 AM. We only know because the Paypal payment information came through on these registrations.

Are you referring to the notification emails of any of your JotForm? As I check your email history log, I didn't see any emails failed. I've checked some of the emails in our bounce list and they are not listed there as well.

If you are referring to any particular JotForm or email address, please let us know. We will be happy to investigate the issue further. Also, we request you to go through the guide below that can help you with troubleshooting email delivery issues.

http://www.jotform.com/help/208-How-to-setup-email-alerts-to-prevent-email-bouncing-related-issues 

Hope this information helps! Please get back to us if the issue still persists. We will be happy to assist you further.