Hi, we have a custom checkbox in our customer record and we want to create an unsubscribe functionality so customers can request to uncheck that field. What is the most secure way to do it? I was thinking of a Suitelet with Google CAPTCHA. Will that be secure enough? Do you have any workaround so that the link we send out cannot be repeatedly used by bots?

You can create a Suitelet with unique links generated via some salt(encryption) and only usable once. No need of google catcha and not re-usable.

Great idea! Thank you!