In smart mail, you can add contacts in the Cc and Bcc lines, and there are two ways to do it, depending on the situation:

1) If you would like to Cc a contact for all the recipients in one smart mail, go to Edit Template and add the contact in the Cc line under the Smart Mail Template title.

2) If you would like to Cc a contact for just one recipient, click on the contact in the left sidebar and then add the contact in the Cc line under the Personalizing Message For XXX page.