I get over 100 email notifications for one submission

How come I'm receiving over 100 of the same exact email notifications for one submission? 

As I check your form submissions, I see that there are multiple submissions of the same entry. For each submission, you'll be receiving an email notification. It seems that your JotForm is being spammed since we notice the same IP address for all these submissions. Please check these submissions from the submissions view. We've now banned the IP address where these submissions came from.

Also, it would be helpful if you can add a captcha field on your JotForm to avoid such spamming.

Hope this information helps. If you need any further assistance, please get back to us. We will be happy to help.

That IP address will still need to make submissions in the future. So they can't be banned. Can you reset the IP address? Also, if I add a captcha will that solve the problem? 

Yes, that should solve the problem with spam.