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.
We have a list of IP addresses, mail servers and domain names available in this user guide. However, the IP list might not be helpful because our IP addresses is constantly changing. You can ask your email provider to whitelist the mail servers and domain list instead. Here's the link: https://www.jotform.com/help/145-Whitelisting-JotMails-IP-Addresses.
If you're still having email issues, we recommend you to use your own SMTP server as the Sender Email. Here's a guide: How-to-Setup-SMTP-for-a-Form.
Hope that helps. Thank you.