How can we make sure that only new customers are redeeming our offer on certain funnels? Is there code we could use to check if the email already exists in Funnelish and not let them check out?
It’s impossible without having your own server that collects emails and checks against a secure remote database. there is no other way to do it safely in the client side using JavaScript, unless perhaps a tool like Zapier or similar no-code options might have a solution.
sorry for the delay
Hi there,
I know this thread is from 2022, but adding an updated note in case anyone is still exploring this 
At the moment, Funnelish doesn’t have a built-in way to block repeat purchases based on email. This kind of check can’t be done securely on the page itself, since client-side code can be bypassed.
If you need to enforce this, the typical approach is to handle it outside of Funnelish. For example, you can:
• Use a tool like Zapier to check if the email already exists and trigger follow-up actions
• Or manage this logic through your own backend/database before allowing access to the offer
Here’s a guide that may help if you’re exploring automation-based setups: