Why have I stopped receiving emails when someone completes a JotForm?

I have checked the email history for your email address and  I can see the failed emails, this is because your email address is currently in our bounce list, I have removed it and you should receive emails from most of your forms as you're using the email address at least in the recent edited forms. 

I will also suggest you to check this guide about how to avoid bouncing: How-to-Prevent-Email-Bouncing-Related-Issues

Here is also a guide that will help you to check and remove an email address from our bounce list: How-to-Remove-Your-Email-Address-from-Bounce-List

Hope this helps.