In SharePoint designer 2010, workflow to send emails, we cannot find BCC (Blind Carbon Copy) column. We can see only To and CC (Carbon Copy) options with Subject and Body.
If we have the requirement to include users in BCC, we can do that by using the steps below,
Complete the Send Mail activity and click on OK. Select Email task in the workflow, click on “Advanced Options” on the top of the ribbon.
We can see “Send an Email Properties” window. In BCC column we can add users to include BCC. Browse users in workflow click on (…) on BCC Column. Add users and click on OK. Click on Ok to close “Send an Email…” window.
Save and publish workflow.