JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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.
We have a user guide that shows our IP addresses, mail servers and domains, here's the link: https://www.jotform.com/help/145-Whitelisting-JotMails-IP-Addresses. However, this is no longer useful since our IP address keeps on changing. To avoid email bouncing issues, use your own SMTP settings for the sender email. Here's a guide: https://www.jotform.com/help/244-How-to-Setup-SMTP-for-a-Form
Also, we had an email issues recently wherein JotForm emails are falling in to spam folder. Could you please check your email spam section? If you find JotForm emails please select all of them and mark them as not spam.
Hope that helps. If you need anything else, please contact us again. We'll be glad to assist you.