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 your following form: http://www.jotformpro.com/form/51354683383965, and two of the recipients were in bounce list: https://www.jotform.com/help/262-How-to-Remove-Your-Email-Address-from-Bounce-List
They have now been white-listed, so this should solve the problem. In addition to this, I would recommend you to white-list our IP addresses and domain names(or ask your email provider to do it), in order to prevent this from happening again: https://www.jotform.com/help/145-Whitelisting-JotMails-IP-Addresses
If there is another form where notifications are not being delivered, please let us know, we will be glad to assist you.