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.
Not quite sure if I understand your concern correctly.
When you say "opt in", are you referring to sending specific email notifications based on a tick box?
If that's the case, it is possible using the Conditional logic, you can check this guide on how to send notifications based on user inputs: http://www.jotform.com/help/167-How-to-send-to-a-specific-email-address-based-on-a-selection
Let us know if I misunderstood your concern.