What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
I checked the email address and found it in our bounce list, the reason is below:
Reason(s) : smtp; 550 5.7.1 Service unavailable; client [**.***.**.**] blocked using dnsbl.sorbs.net
When your email address is in our bounce list you will not receive emails until you remove the email address from our bounce list, this guide will help you with that: How-to-Remove-Your-Email-Address-from-Bounce-List
Here is a guide that will help you to set up your emails to avoid bouncing: How-to-Setup-Email-Alerts-to-Prevent-Email-Bouncing-Related-Issues
As you're using our default sender email addresses, if the issue persists then you should ask your email provider to white-list our IP addresses: Whitelisting-JotMails-IP-Addresses
Hope this helps.