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.
This may have been caused by one of the IPs used by JotForm. For the email alerts being sent to your user, can you test if using an SMTP email address would resolve this issue?
If you need to learn how to setup SMTP on your account, please follow this guide: https://www.jotform.com/help/244-How-to-Setup-SMTP-for-a-Form