Another vote here for this feature!
In our firm’s particular case, we are having difficulty capturing marketing emails sent through HubSpot in our emai archiving software, Smarsh. I’ve tried working with both HubSpot & Smarsh on this issue and we are unable to come up with a solution at this point. If we could blind copy our firm’s “info” email account, I believe it would allow us to capture these emails in our archiving software, as the software is supposed to capture all emails sent/received with our domain address. We are currently only able to see the HubSpot emails in Smarsh when someone replies to the original email sent through HubSpot.