Anyone who is a follower of a candidate will be BCC'd on emails sent via Workable to the candidate. Followers are listed at the top of a candidate's Timeline and they will receive notifications about actions taken on the candidate's profile (e.g. being BCC'd on emails or receiving alerts in Workable when someone leaves an evaluation).
Here we can see the profile photos for the three current followers. These three users will be BCC'd when an email is sent. Users become followers when they interact with a candidate's profile (e.g. when they add a comment, send an email, leave an evaluation, etc.). You can remove a follower by hovering over their icon and clicking the X that appears.