Idea to get consent to keep candidate data in the system

Summary:

Hi all,

We are planning to purge the data of candidates who did not agree to have their personal information retained in our system. We plan to use Campaigns to get candidates' responses by adding a response button in the email. We aim to send out the email to all external candidates, but using Campaigns, only those who agree to receive marketing communications will be recipients, which is not ideal.

Has anyone here done candidate purging before? Please feel free to share your process here.

Also, if anyone has any suggestions on how we can send the email to all candidates and get their responses, it would be much appreciated.