Why is my email all of sudden boucing back?

There are several reasons why your email address may have been added to the bounce list. It could be due to a non-existent/inactive email address, your mail server being unavailable, your email server has rejected the emails due to suspected spam, your mailbox is full or JotForm is on your blacklist. JotForm will stop sending emails when your email address is on the bounce list.

Inside of this guide, you can find how to remove the email address from the bounce list:

How to Remove Your Email Address from Bounce List

To prevent bouncing of your emails, please check this guide:

How to Prevent Email Bouncing Related Issues

Also, you should contact your email provider and ask them to Whitelist JotMails IP Addresses.

Hope this will help.