Can we add the CTA label to the email activity bcc to timeline?

Our CSMs use CTAs to remind them to reach out to customers to schedule meetings, then take notes and record their meeting follow-up emails from within the CTA. That way when they look at Timeline for the account, they can immediately see which meeting notes and follow-up emails went with the meeting because of the CTA label.

Is there a way to apply to CTA label to an email activity that has been created through BCC'ing to Timeline? We'd love to be able to keep everything organized.