Email opt-out in Zoho survey?

Email opt-out in Zoho survey?

Hello Users:

We are using Zoho survey on our website for a questionnaire that displays results in the browser window. Before displaying the results, we ask for contact information. The contact information is then sent to Zoho CRM and parsed by the email parser to create a lead. I can't figure out how to enable a double opt-in selection so the CRM can mark this contact as do not email.

What is the best practice to accomplish this? Maybe I am missing a setting in Surveys or the CRM for parsed emails? 

FYI: We are not using a zoho webform for this. Maybe I need to? 


Thanks