Allowing individual clients to opt out of Support Ticket Feedback emails is quite an undertaking from a development standpoint, as we would be introducing new functionality to the client database and interface. That being said, due to the complexity and moving parts of how clients work in WHMCS, we have little interest in introducing that functionality. We've looked through the feature request system and noticed a few different requests dealing with how we handle Support Ticket Feedback.

Would allowing admins the ability to determine which departments Support Ticket Feedback emails get sent to help in solving these issues? You can find the feature request here: https://requests.whmcs.com/responses/configure-specific-support-departments-for-support-ticket-feedback