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.
You may check this guide that will help you to avoid bouncing issues: How-to-Prevent-Email-Bouncing-Related-Issues
If possible, you could also set up your custom sender email address using the SMTP method, this way you avoid emails being blocked or sending to the spam folder because of the server blocking the JotForm mail sender IP address.
Setting up the SMTP sender will also help you to get more control over how the emails are sent since you're using your own mail server info.
Here is the guide that will help you to set up the SMTP sender in your form: How-to-Setup-SMTP-for-a-Form
Hope this helps.