Email Template - Add Recipients Dynamically

Howdy CRM World,

Just got a bizzard requirement where in when my sales ppl insert email template (either from within CRM or outlook), apart from automatically filling in email subject & description, they also want to add a mailbox address or any user automatically to the email To/bcC recipients list. Is it even possible?

I know there is no place in email template to configure this or OOB way of achieving. Looking for valuable suggestions.

Thanks in advance